Physics Book - User contributions [en]

Rutherford Experiment and Atomic Collisions

2017-11-27T22:21:59Z

Dveludhandi6: /* References */

Claimed by: dveludhandi6 (Fall 2017)

==Rutherford's Gold Foil Experiment==

Rutherford's Gold Foil Experiment helped detect that there was a large positively charged mass in the center of an atom: the nucleus. The experiment was done through the use of atomic collisions. Under the instruction of Rutherford, Hans Geiger and Ernest Marsden pointed a beam of alpha particles at a thin foil of metal and measured the scattering pattern by using a fluorescent screen. The scientists noted that some alpha particles bounced in random directions. This was not originally hypothesized due to the idea that, at most the alpha particle should experience only a 90° scattering angle. This helped lead to the discovery of the nucleus and a highly compact positively charged center.

[[File:Atomic Collisions.png|300px|thumb|right|A model of atomic collisions involving an alpha particle]]

===History===
Around the early 1900s, very little was known about atoms besides the ground breaking experiments conducted by J.J. Thompson in 1897. Thompson discovered what we call the electron. He hypothesized that electrons were negatively charged particles. It was also speculated that there must be a positive charge to balance out the negative charge from the electron. This "Plum Pudding Model" was invented by Thompson. This model assumed that matter consists of atoms which are overall positively charged, but with some type of negative electron charge throughout it. The electrons function as the "plum" which was evenly distributed through a positively charged "pudding".

Rutherford studied the particles that uranium and its derivatives emitted and how these particles affected certain materials.
Rutherford created a method to record the position of each alpha particle by circling the bombarded object with a ZnS coated sheet. This sheet would emit a flash of light when hit by an alpha particle, allowing Rutherford to accurately measure the deflection of each alpha particle. This gave Rutherford a counting mechanism for theses particles he wanted to study. Rutherford then began to study the angles that negatively charged particles deflected when they collided with a thin metal foil. This was the beginning of his most famous study: the gold foil experiment. Knowing the relative mass of these negatively charged particles and their quick speed, he hypothesized that they would pierce the metal foil but then collide with the atoms dispersed inside the foil resulting in the small deflections. These deflections were extremely small, usually by a degree. In 1911, Ernest Rutherford took this experiment further and worked with his assistants, Hans Geiger and Ernest Marsden to carry out an experiment that tested the plum pudding model. They shot alpha (helium 2+) particles at gold foil in order to measure the deflection of the particles as they come off of the other side. They decided to see if these deflections could occur at larger angles greater than 90 degrees. Through countless trials, they found an extremely small portion of these deflections to occur at angles larger than 90 degrees. Rutherford wondered how these large deflections occurred and concluded that there existed an extremely small and positively charged area in the atom that resulted in these huge deflections. He eventually named this area the nucleus. What happened during these deflections was that most particles would become slightly deflected by small angles due to the positive atoms. However, some would collide directly with nucleus resulting int the deflections that were greater than 90 degrees. These occurred rarely because the nucleus was such a small size so the probability of these atoms hitting the nucleus was very low. This experiment helped indicate that the atom is made predominantly of empty space with a small nucleus with protons and electrons placed extremely far away from the nucleus in their own cloud. Rutherford devised the name “proton” to describe the positive particles in the nucleus. He thought that a neutral particle existed in the nucleus too, but its existence wasn’t confirmed until 1932 when James Chadwick proved it.

===A Mathematical Model===

Rutherford modeled the effect the alpha particle has on the electrons of the gold atom. He did this by calculating the potential electric energy between the particle and the atom using the formula below. Rutherford came up with several equations to numerically describe these deflections. Based on the equations below, the number of particles scattered at a certain angle is directly proportional to the thickness of the metal foil and the square of the nucleus’ charge but inversely proportional to the particle’s velocity raised to the fourth power.

<math>{U_{elec}} = {\frac{1}{4πε_0}}{\frac{q_{α}q_{Au}}{r}} </math>

Where:

r = center to center distance between particle and atom

<math>{\frac{1}{4πε_0}} = {9*10^9}{\frac {N*m^2}{C^2}}</math>

<math>{q_α}</math> = charge of alpha particle

<math>{q_{Au}}</math> = charge of gold nucleus

In this instance the charge of the alpha particle is equal to 2e and the charge of the gold particle is equal to 79e.

Another important part of atomic collisions is that they are inelastic collisions. This is shown by the conservation of both momentum and kinetic energy.
Take the alpha particle and gold particle for example.

<math> {\vec{p_{α,i}}} = {\vec{p_{α,f}}}+ {\vec{p_{Au,f}}} </math>

<math> {\vec{K_{α,i}}} = {\vec{K_{α,f}}}+ {\vec{K_{Au,f}}} </math>

Where <math>{\vec{p}}</math> is momentum and <math>{\vec{K}}</math> is kinetic energy.

===A Computational Model===

Much like the mathematical model, the collision can be modeled computationally using the same formulas. In order to view this better, here is an example of one collision using the [https://trinket.io/embed/glowscript/bc8f4d2b99 Rutherford Scattering Model.]

==Example Problems==

===Simple===

The scattering of alpha particles from nuclei is mathematically modeled from the Coulomb force and treated as an orbit. For a ZnS detector at a specific angle with respect to the incident beam, the number of particles per unit area striking the detector is given by the Rutherford formula: 
<math> N(θ) = {\frac{N_inLZ^2k^2e^4}{4r^2KE^2sin^4(θ/2)}}
</math>
where 
<math> N_i = \text {number of incident alpha particles} </math> 
<math>n = \text {atoms per unit volume in target}</math> 
<math>L = \text {thickness of target}</math> 
<math>Z = \text {atomic number of target}</math> 
<math>e = \text {electron charge}</math> 
<math>k = \text {Coulomb's constant}</math> 
<math>r = \text {target to detector distance}</math> 
<math>KE = \text {kinetic energy of alpha}</math> 
<math>θ = \text {scattering angle} </math> 

Find the number of particles per unit area striking the detector given the following values: 
<math> N_i = 5 </math> alpha particles 
<math>n = 8.4866 * 10^{22} \text {atoms in 1} cm^3 </math> 
<math>L = 1 cm </math> 
<math>Z = 26</math> 
<math>e = -1 </math> 
<math>k = 8.988 * 10^9 </math> 
<math>r = 10 cm</math> 
<math>KE = (1/2)*m*v^2 </math> where <math> v_a = 1.53 * 10^7 m/s \text {and mass of the alpha particle is} 6.64424*10^27 kg </math> 
<math>θ = 0.18 degrees </math> 

====Solution====

Plug each number into the equation (make sure units cancel).

<math> N(0.18) = {\frac{5*8.4866*10^{22}*1*26^2*{(8.988*10^9)}^2*-1^4}{4*10^2*{((1/2)(6.64424*10^27){(1.53*10^-7)}^2)}^2*sin^4(0.18/2)}}
</math>

= 1.57341 * 10^27 particles striking the surface per cm

===Difficult===
A proton and an electron are a distance <math>{7.2*10^{-9}m}</math> apart. What is the electric potential energy of the system consisting of the proton and the electron?

====Solution====
<math>{U_{elec}} = {\frac{1}{4πε_0}}{\frac{q_{+}q_{-}}{r}} </math>

<math>{U_{elec}} = {9*10^{9}}{\frac {N*m^2}{C^2}}*{\frac{1.6*10^{-19}*(-1.6*10^{-19})}{7.2*10^{-9}}} = {-3.2*10^{-28}}{J}</math>

==Connectedness==
This topic is related to the study of chemical engineering. Without the discovery of the nucleus, any progress in this field would be limited based on the interaction of atomic particles. This would also hinder the field medicine for very similar reason. Much of the understanding of sciences has its roots in the understanding of the atom and its functions. This experiment and the idea of atomic collisions helped to widen the atomic grasp. One of the best industrial examples of atomic collisions is the Large Hadron Collider.

==History==

With the knowledge of the plum pudding model of the atom, Ernst Rutherford and a small group of scientists set out to discover the properties behind alpha particles. The experiment, now known as the Gold Foil Experiment, was used to test this in 1911. It involved launching alpha particles at a small piece of gold foil. It was hypothesized that the alpha particle would be deflected at times, but at an angle because it was assumed that the alpha particle was more dense than the gold foil atom. They registered deflected particles through light emissions that would occur when the alpha particle hit the light source. Much to their surprise, some of the alpha particles they launched bounced straight back. This demonstrated that the gold particle was more massive than expected. It led to the discovery that the atom contained a positively charged nucleus. This was a major break through in the study of the atom in that it showed what the atoms composition was and how it act around other atoms.

[[File:Gold foil experiment.png|600px|thumb|left|Above is a model of the Gold Foil experiment performed in Rutherford's lab.]]

==References==

Chabay, R.W., & Sherwood, B.A. (2015). Collisions. In Fiorillo, J. Editor & Rentrop, A. Editor (Eds.), Matter and Interactions (383-410). John Wiley & Sons, Inc.
[[Category: Collisions]]

“Ernest Rutherford.” New Page 2, chemed.chem.purdue.edu/genchem/history/gold.html.

"History of Rutherford Experiment". HyperPhysics. Web. 03 Dec. 2015. Retrieved from: <http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html>.

Rutherford Experiment and Atomic Collisions

2017-11-27T22:19:28Z

Dveludhandi6: /* Rutherford's Gold Foil Experiment */

Claimed by: dveludhandi6 (Fall 2017)

==Rutherford's Gold Foil Experiment==

Rutherford's Gold Foil Experiment helped detect that there was a large positively charged mass in the center of an atom: the nucleus. The experiment was done through the use of atomic collisions. Under the instruction of Rutherford, Hans Geiger and Ernest Marsden pointed a beam of alpha particles at a thin foil of metal and measured the scattering pattern by using a fluorescent screen. The scientists noted that some alpha particles bounced in random directions. This was not originally hypothesized due to the idea that, at most the alpha particle should experience only a 90° scattering angle. This helped lead to the discovery of the nucleus and a highly compact positively charged center.

[[File:Atomic Collisions.png|300px|thumb|right|A model of atomic collisions involving an alpha particle]]

===History===
Around the early 1900s, very little was known about atoms besides the ground breaking experiments conducted by J.J. Thompson in 1897. Thompson discovered what we call the electron. He hypothesized that electrons were negatively charged particles. It was also speculated that there must be a positive charge to balance out the negative charge from the electron. This "Plum Pudding Model" was invented by Thompson. This model assumed that matter consists of atoms which are overall positively charged, but with some type of negative electron charge throughout it. The electrons function as the "plum" which was evenly distributed through a positively charged "pudding".

Rutherford studied the particles that uranium and its derivatives emitted and how these particles affected certain materials.
Rutherford created a method to record the position of each alpha particle by circling the bombarded object with a ZnS coated sheet. This sheet would emit a flash of light when hit by an alpha particle, allowing Rutherford to accurately measure the deflection of each alpha particle. This gave Rutherford a counting mechanism for theses particles he wanted to study. Rutherford then began to study the angles that negatively charged particles deflected when they collided with a thin metal foil. This was the beginning of his most famous study: the gold foil experiment. Knowing the relative mass of these negatively charged particles and their quick speed, he hypothesized that they would pierce the metal foil but then collide with the atoms dispersed inside the foil resulting in the small deflections. These deflections were extremely small, usually by a degree. In 1911, Ernest Rutherford took this experiment further and worked with his assistants, Hans Geiger and Ernest Marsden to carry out an experiment that tested the plum pudding model. They shot alpha (helium 2+) particles at gold foil in order to measure the deflection of the particles as they come off of the other side. They decided to see if these deflections could occur at larger angles greater than 90 degrees. Through countless trials, they found an extremely small portion of these deflections to occur at angles larger than 90 degrees. Rutherford wondered how these large deflections occurred and concluded that there existed an extremely small and positively charged area in the atom that resulted in these huge deflections. He eventually named this area the nucleus. What happened during these deflections was that most particles would become slightly deflected by small angles due to the positive atoms. However, some would collide directly with nucleus resulting int the deflections that were greater than 90 degrees. These occurred rarely because the nucleus was such a small size so the probability of these atoms hitting the nucleus was very low. This experiment helped indicate that the atom is made predominantly of empty space with a small nucleus with protons and electrons placed extremely far away from the nucleus in their own cloud. Rutherford devised the name “proton” to describe the positive particles in the nucleus. He thought that a neutral particle existed in the nucleus too, but its existence wasn’t confirmed until 1932 when James Chadwick proved it.

===A Mathematical Model===

Rutherford modeled the effect the alpha particle has on the electrons of the gold atom. He did this by calculating the potential electric energy between the particle and the atom using the formula below. Rutherford came up with several equations to numerically describe these deflections. Based on the equations below, the number of particles scattered at a certain angle is directly proportional to the thickness of the metal foil and the square of the nucleus’ charge but inversely proportional to the particle’s velocity raised to the fourth power.

<math>{U_{elec}} = {\frac{1}{4πε_0}}{\frac{q_{α}q_{Au}}{r}} </math>

Where:

r = center to center distance between particle and atom

<math>{\frac{1}{4πε_0}} = {9*10^9}{\frac {N*m^2}{C^2}}</math>

<math>{q_α}</math> = charge of alpha particle

<math>{q_{Au}}</math> = charge of gold nucleus

In this instance the charge of the alpha particle is equal to 2e and the charge of the gold particle is equal to 79e.

Another important part of atomic collisions is that they are inelastic collisions. This is shown by the conservation of both momentum and kinetic energy.
Take the alpha particle and gold particle for example.

<math> {\vec{p_{α,i}}} = {\vec{p_{α,f}}}+ {\vec{p_{Au,f}}} </math>

<math> {\vec{K_{α,i}}} = {\vec{K_{α,f}}}+ {\vec{K_{Au,f}}} </math>

Where <math>{\vec{p}}</math> is momentum and <math>{\vec{K}}</math> is kinetic energy.

===A Computational Model===

Much like the mathematical model, the collision can be modeled computationally using the same formulas. In order to view this better, here is an example of one collision using the [https://trinket.io/embed/glowscript/bc8f4d2b99 Rutherford Scattering Model.]

==Example Problems==

===Simple===

The scattering of alpha particles from nuclei is mathematically modeled from the Coulomb force and treated as an orbit. For a ZnS detector at a specific angle with respect to the incident beam, the number of particles per unit area striking the detector is given by the Rutherford formula: 
<math> N(θ) = {\frac{N_inLZ^2k^2e^4}{4r^2KE^2sin^4(θ/2)}}
</math>
where 
<math> N_i = \text {number of incident alpha particles} </math> 
<math>n = \text {atoms per unit volume in target}</math> 
<math>L = \text {thickness of target}</math> 
<math>Z = \text {atomic number of target}</math> 
<math>e = \text {electron charge}</math> 
<math>k = \text {Coulomb's constant}</math> 
<math>r = \text {target to detector distance}</math> 
<math>KE = \text {kinetic energy of alpha}</math> 
<math>θ = \text {scattering angle} </math> 

Find the number of particles per unit area striking the detector given the following values: 
<math> N_i = 5 </math> alpha particles 
<math>n = 8.4866 * 10^{22} \text {atoms in 1} cm^3 </math> 
<math>L = 1 cm </math> 
<math>Z = 26</math> 
<math>e = -1 </math> 
<math>k = 8.988 * 10^9 </math> 
<math>r = 10 cm</math> 
<math>KE = (1/2)*m*v^2 </math> where <math> v_a = 1.53 * 10^7 m/s \text {and mass of the alpha particle is} 6.64424*10^27 kg </math> 
<math>θ = 0.18 degrees </math> 

====Solution====

Plug each number into the equation (make sure units cancel).

<math> N(0.18) = {\frac{5*8.4866*10^{22}*1*26^2*{(8.988*10^9)}^2*-1^4}{4*10^2*{((1/2)(6.64424*10^27){(1.53*10^-7)}^2)}^2*sin^4(0.18/2)}}
</math>

= 1.57341 * 10^27 particles striking the surface per cm

===Difficult===
A proton and an electron are a distance <math>{7.2*10^{-9}m}</math> apart. What is the electric potential energy of the system consisting of the proton and the electron?

====Solution====
<math>{U_{elec}} = {\frac{1}{4πε_0}}{\frac{q_{+}q_{-}}{r}} </math>

<math>{U_{elec}} = {9*10^{9}}{\frac {N*m^2}{C^2}}*{\frac{1.6*10^{-19}*(-1.6*10^{-19})}{7.2*10^{-9}}} = {-3.2*10^{-28}}{J}</math>

==Connectedness==
This topic is related to the study of chemical engineering. Without the discovery of the nucleus, any progress in this field would be limited based on the interaction of atomic particles. This would also hinder the field medicine for very similar reason. Much of the understanding of sciences has its roots in the understanding of the atom and its functions. This experiment and the idea of atomic collisions helped to widen the atomic grasp. One of the best industrial examples of atomic collisions is the Large Hadron Collider.

==History==

With the knowledge of the plum pudding model of the atom, Ernst Rutherford and a small group of scientists set out to discover the properties behind alpha particles. The experiment, now known as the Gold Foil Experiment, was used to test this in 1911. It involved launching alpha particles at a small piece of gold foil. It was hypothesized that the alpha particle would be deflected at times, but at an angle because it was assumed that the alpha particle was more dense than the gold foil atom. They registered deflected particles through light emissions that would occur when the alpha particle hit the light source. Much to their surprise, some of the alpha particles they launched bounced straight back. This demonstrated that the gold particle was more massive than expected. It led to the discovery that the atom contained a positively charged nucleus. This was a major break through in the study of the atom in that it showed what the atoms composition was and how it act around other atoms.

[[File:Gold foil experiment.png|600px|thumb|left|Above is a model of the Gold Foil experiment performed in Rutherford's lab.]]

==References==

"History of Rutherford Experiment". HyperPhysics. Web. 03 Dec. 2015. Retrieved from: <http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html>.

Chabay, R.W., & Sherwood, B.A. (2015). Collisions. In Fiorillo, J. Editor & Rentrop, A. Editor (Eds.), Matter and Interactions (383-410). John Wiley & Sons, Inc.
[[Category: Collisions]]

Rutherford Experiment and Atomic Collisions

2017-11-27T21:23:33Z

Dveludhandi6:

Claimed by: dveludhandi6 (Fall 2017)

==Rutherford's Gold Foil Experiment==

Rutherford's Gold Foil Experiment helped detect that there was a large positively charged mass in the center of an atom. The experiment was done through the use of atomic collisions. Under the instruction of Rutherford, Hans Geiger and Ernest Marsden pointed a beam of alpha particles at a thin foil of metal and measured the scattering pattern by using a fluorescent screen. The scientists noted that some alpha particles bounced in random directions. This was not originally hypothesized due to the idea that, at most the alpha particle should experience only a 90° scattering angle. This helped lead to the discovery of the nucleus and a highly compact positively charged center.

[[File:Atomic Collisions.png|300px|thumb|right|A model of atomic collisions involving an alpha particle]]

===History===
Around the early 1900s, very little was known about atoms besides the ground breaking experiments conducted by J.J. Thompson in 1897. Thompson discovered what we call the electron. He hypothesized that electrons were negatively charged particles. It was also speculated that there must be a positive charge to balance out the negative charge from the electron. This "Plum Pudding Model" was invented by Thompson. This model assumed that matter consists of atoms which are overall positively charged, but with some type of negative electron charge throughout it. The electrons function as the "plum" which was evenly distributed through a positively charged "pudding".

In 1911, Ernest Rutherford, Hans Geiger, and Ernest Marsden carried out an experiment to test the plum pudding model. They shot alpha (helium 2+) particles at gold foil in order to measure the deflection of the particles as they come off of the other side. Rutherford created a method to record the position of each alpha particle by circling the bombarded object with a ZnS coated sheet. This sheet would emit a flash of light when hit by an alpha particle, allowing Rutherford to accurately measure the deflection of each alpha particle. He hypothesized that there would be a small amount of deflection due to the charge in the metal atom's subatomic particles. He noticed that some of the particles were deflected larger than 90 degrees. As a result, he was able to deduce that a majority of the particles went straight through the atom, but some of the particles bounced off of a small, positively charged mass in the center of the atom. This experiment helped indicate that the atom is made predominantly of empty space with a small nucleus with protons and electrons placed extremely far away from the nucleus in their own cloud.

===A Mathematical Model===

Rutherford modeled the effect the alpha particle has on the electrons of the gold atom. He did this by calculating the potential electric energy between the particle and the atom using the formula below.

<math>{U_{elec}} = {\frac{1}{4πε_0}}{\frac{q_{α}q_{Au}}{r}} </math>

Where:

r = center to center distance between particle and atom

<math>{\frac{1}{4πε_0}} = {9*10^9}{\frac {N*m^2}{C^2}}</math>

<math>{q_α}</math> = charge of alpha particle

<math>{q_{Au}}</math> = charge of gold nucleus

In this instance the charge of the alpha particle is equal to 2e and the charge of the gold particle is equal to 79e.

Another important part of atomic collisions is that they are inelastic collisions. This is shown by the conservation of both momentum and kinetic energy.
Take the alpha particle and gold particle for example.

<math> {\vec{p_{α,i}}} = {\vec{p_{α,f}}}+ {\vec{p_{Au,f}}} </math>

<math> {\vec{K_{α,i}}} = {\vec{K_{α,f}}}+ {\vec{K_{Au,f}}} </math>

Where <math>{\vec{p}}</math> is momentum and <math>{\vec{K}}</math> is kinetic energy.

===A Computational Model===

Much like the mathematical model, the collision can be modeled computationally using the same formulas. In order to view this better, here is an example of one collision using the [https://trinket.io/embed/glowscript/bc8f4d2b99 Rutherford Scattering Model.]

==Example Problems==

===Simple===

The scattering of alpha particles from nuclei is mathematically modeled from the Coulomb force and treated as an orbit. For a ZnS detector at a specific angle with respect to the incident beam, the number of particles per unit area striking the detector is given by the Rutherford formula: 
<math> N(θ) = {\frac{N_inLZ^2k^2e^4}{4r^2KE^2sin^4(θ/2)}}
</math>
where 
<math> N_i = \text {number of incident alpha particles} </math> 
<math>n = \text {atoms per unit volume in target}</math> 
<math>L = \text {thickness of target}</math> 
<math>Z = \text {atomic number of target}</math> 
<math>e = \text {electron charge}</math> 
<math>k = \text {Coulomb's constant}</math> 
<math>r = \text {target to detector distance}</math> 
<math>KE = \text {kinetic energy of alpha}</math> 
<math>θ = \text {scattering angle} </math> 

Find the number of particles per unit area striking the detector given the following values: 
<math> N_i = 5 </math> alpha particles 
<math>n = 8.4866 * 10^{22} \text {atoms in 1} cm^3 </math> 
<math>L = 1 cm </math> 
<math>Z = 26</math> 
<math>e = -1 </math> 
<math>k = 8.988 * 10^9 </math> 
<math>r = 10 cm</math> 
<math>KE = (1/2)*m*v^2 </math> where <math> v_a = 1.53 * 10^7 m/s \text {and mass of the alpha particle is} 6.64424*10^27 kg </math> 
<math>θ = 0.18 degrees </math> 

====Solution====

Plug each number into the equation (make sure units cancel).

<math> N(0.18) = {\frac{5*8.4866*10^{22}*1*26^2*{(8.988*10^9)}^2*-1^4}{4*10^2*{((1/2)(6.64424*10^27){(1.53*10^-7)}^2)}^2*sin^4(0.18/2)}}
</math>

= 1.57341 * 10^27 particles striking the surface per cm

===Difficult===
A proton and an electron are a distance <math>{7.2*10^{-9}m}</math> apart. What is the electric potential energy of the system consisting of the proton and the electron?

====Solution====
<math>{U_{elec}} = {\frac{1}{4πε_0}}{\frac{q_{+}q_{-}}{r}} </math>

<math>{U_{elec}} = {9*10^{9}}{\frac {N*m^2}{C^2}}*{\frac{1.6*10^{-19}*(-1.6*10^{-19})}{7.2*10^{-9}}} = {-3.2*10^{-28}}{J}</math>

==Connectedness==
This topic is related to the study of chemical engineering. Without the discovery of the nucleus, any progress in this field would be limited based on the interaction of atomic particles. This would also hinder the field medicine for very similar reason. Much of the understanding of sciences has its roots in the understanding of the atom and its functions. This experiment and the idea of atomic collisions helped to widen the atomic grasp. One of the best industrial examples of atomic collisions is the Large Hadron Collider.

==History==

With the knowledge of the plum pudding model of the atom, Ernst Rutherford and a small group of scientists set out to discover the properties behind alpha particles. The experiment, now known as the Gold Foil Experiment, was used to test this in 1911. It involved launching alpha particles at a small piece of gold foil. It was hypothesized that the alpha particle would be deflected at times, but at an angle because it was assumed that the alpha particle was more dense than the gold foil atom. They registered deflected particles through light emissions that would occur when the alpha particle hit the light source. Much to their surprise, some of the alpha particles they launched bounced straight back. This demonstrated that the gold particle was more massive than expected. It led to the discovery that the atom contained a positively charged nucleus. This was a major break through in the study of the atom in that it showed what the atoms composition was and how it act around other atoms.

[[File:Gold foil experiment.png|600px|thumb|left|Above is a model of the Gold Foil experiment performed in Rutherford's lab.]]

==References==

"History of Rutherford Experiment". HyperPhysics. Web. 03 Dec. 2015. Retrieved from: <http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html>.

Chabay, R.W., & Sherwood, B.A. (2015). Collisions. In Fiorillo, J. Editor & Rentrop, A. Editor (Eds.), Matter and Interactions (383-410). John Wiley & Sons, Inc.
[[Category: Collisions]]

SI Units

2017-04-09T22:01:27Z

Dveludhandi6: /* Derived SI units */

This page is about SI Units. This page is created by Jinyoung Lee. Improved by Ryan Yeung. Claimed by Deepti Veludhandi 2017.
==The Main Idea==

SI unit stands for the 'International System of Units'. It is the modern form of the metric system, and is the most widely used system of measurement. It is used among almost all of the larger countries, with the major exception being the United States. It is used whenever scientific observations or measurements are made. It is made up of 7 standard units. It justifies twenty-two named units, and includes many more unnamed coherent derived units. The system also establishes a set of twenty prefixes to the unit names and unit symbols that may be used when specifying multiples and fractions of the units.

===A Mathematical Model===

There are some mathematical operations required to translate a non-SI unit to SI unit. These are generally simple operations such as addition, subtraction, division, and multiplication. For example <math>{\frac{lb}{2.2}} = kg</math> Since 1 kg(SI unit) is equal to 2.2 lb, to change lb to SI unit, or kg, lb has to be divided by 2.2.

Another example can be length. <math>{\frac{inch}{0.394}} = cm</math> Same method used to change lb to kg. Since 1cm is equal to 0.394inch, inch has to be divided by 0.394 to become SI unit, cm.

These transformations can be done throughout all of the recorded units in the world. In order to preform these simply find the accepted transformation values, and preform a simple division or multiplication operation.

==Base SI units==

[[File:SIbase.jpg]]

This image above shows the base SI units. These units include length, mass, time, electric current, temperature, substance amount, and light intensity. There also exist a variety of other units that are not as commonplace as these other 7.

==Prefix==

Mass, length or any numbers in physics can be very small or very large. Electrons can be a great example. The mass of electron is 0.0000000000000000000000910938356g or 9.10938356 E-31. In SI, prefixes are available to adjust the size of a unit so as to keep the number of those units reasonable. It is kind of difficult to read that number in word. However with the prefix it can be. Image below shows the list of prefixes.

[[File:prefix1.jpg]]

These prefixes are incredibly useful for clarity purposes. The prefixes listed are incredibly useful for a speaker or writer in order to help ease their use.

==Derived SI units==

[[File:Relationdiagram.jpg]]

This image above shows the relationships between many units used in physics based on base SI units. As we can see, most of the units in physics is related to the SI units. It is because there are many quantities that cannot be expressed by a single base SI unit. For example, when talking about the density, it is volume/mass. Mass has it's own SI unit which is a gram. However volume doesn't. Volume is expressed with derived SI unit, meters cubed. As a result, unit for density is <math>\mathrm{m}^3/\mathrm{g}</math> . Those units are called derived SI units. Units can be combined to create new unit. Some frequently-used combinations have their units named. Here are some examples:

*Watt (W), the unit of power.
**<math>\mathrm{W} = \mathrm{J}/\mathrm{s} \ </math>

*Pascal (Pa), the unit of pressure.
**<math>\mathrm{Pa} = \mathrm{N}/\mathrm{m}^2 \ </math>

*Hertz (Hz), the unit of frequency.
**<math>\mathrm{Hz} = 1/\mathrm{s} = \mathrm{s}^{-1} \ </math>

*Newton (N), the unit of force.
**<math>\mathrm{N} = \mathrm{kg} \cdot \mathrm{m}/\mathrm{s}^2 </math>

*Joule (J), the unit of energy.
**<math>\mathrm{J} = \mathrm{N} \cdot \mathrm{m} = \mathrm{kg} \cdot \mathrm{m}^2/\mathrm{s}^2 </math>

*Coulomb (C), the unit of electric charge.
**<math>\mathrm{C} = \mathrm{A} \cdot \mathrm{s} </math>

*Volt (V), the unit of electric potential or voltage.
**<math>\mathrm{V} = \mathrm{J}/\mathrm{C} = \mathrm{W}/\mathrm{A} \ </math>

The list is incredibly useful for measuring quantities that dont have a standard SI unit already in place.

==Connectedness==
This topic can be applied to every aspect of science. When solving the problem, or even when doing a research, every equation and theory is based on SI units. It is a promise between scientists to use the certain units to reduce the errors or misunderstanding. Therefore, it is very important to know the concept of SI units. This topic is connected to not only physics but also every other scientific subjects. In addition, it might not be familiar in United States, but in most of the other countries they use SI units in ordinary life. SI units create a form of standardization throughout the scientific community. This standardization stems from their connection to fundamental constants. These constants are dependent on naturally occurring laws on Earth. As a result, since these units are connected to these constants that are unchanging no matter what location on Earth they're being observed at, this system of measurement is able to achieve a high level of standardization. This establishes a sense of unity and allows scientists to be working on the same page no matter what nationality they are. It's through the use of these units that the community of scientists as a whole that error can be reduced to a minimum and calculations and findings can be standardized across the globe. Si units also allow scientists to reproduce experiments, and record their results in the same form. This allows for more credibility among findings as well. SI units are also very useful for the use of dimensional analysis. Dimensional analysis is the mathematical problem solving method that essentially means that any number expression can be multiplied by another and its inherent value won't be changed. This vital problem solving idea is only possible due to the fact that SI units can be converted to non SI units with incredible ease. SI units create an incredible amount of standardization throughout the scientific community and have been essential for the production of viable and credible scientific results.

Due to recent events in the scientific community and the new levels of accuracy achieved from the use of modern and scientifically advanced equipment, there have been several discoveries that can redefine how we understand fundamental constants. Since SI units are closely intertwined with fundamental constants, these discoveries have great relevance. Most of these discoveries are in the field of quantum physics which is generally a new field in comparison to other scientific subjects. The technology age has given scientists cutting-edge equipment allowing them to reach results that are more specific and accurate. For example, this equipment can allow them to calculate a more accurate mass of an electron which is an important constant and affects the values of base units in the SI unit system. When discoveries like these directly affect our understanding of fundamental constants, they can have an effect on the SI unit system. However, some discoveries, not all, might only change the value of a constant by a minuscule amount, so the SI units will barely change their values and will most likely not directly affect the way most students solve problems since they tend to use rounding a lot in problems.

==History==

The Metric System was created around the time of the French Revolution and the subsequent deposition of two platinum standards representing the meter and the kilogram, on 22 June 1799, in the Archives de la Republic in Paris can be seen as the first step in the development of the present International System of Units. Each of the base units has root within the physical world. For example the unit of metre is derived from dimensions of the Earth, the kilogram was derived the volume of of one liter of water. These 2 units are the baseline for the remainder of the SI system. The new metric system was originally abandoned by France. In 1837, the metric system was readopted by France, and slowly then became adopted by the scientific community. After this a man named James Clerk Maxwell presented the idea of a number of base units, time, mass, and length. This 3 base units could then be used to derive a series of other measurements throughout the scientific world. However it was quickly discovered that these units cannot describe non-mechanical properties. Most importantly they couldn't properly describe the electrical properties of the world. A man named Giovanni Giorgi, an Italian physicist and electrical engineer, proposed a fourth base unit should be added to the original 3 in order to properly describe the electrical systems of the world. This unit was later decided, in 1935, to be the ampere thus allowing the world to aptly describe electrical systems as well. As the years passed these units began to become more and more commonplace among the world, with many other countries beginning to use the SI system as their main form of measurement. The SI system quickly became the accepted scientific measuring system as well. The use of this system has helped to advance and drive scientific advancement throughout the years.

===Further reading===

SI Units for Clinical Measurement 1st Edition by Donald S. Young

Matter & Interactions, Vol. I: Modern Mechanics, 4nd Edition by R. Chabay & B. Sherwood (John Wiley & Sons 2015)

Base units of the SI, fundamental constants and modern quantum physics by Christian J Bordé

==References==

http://physics.nist.gov/ National institute of standards and Technology.

http://wps.prenhall.com/wps/media/objects/165/169061/blb9ch0104.html Pearson educational site.

Matter & Interactions, Vol. I: Modern Mechanics, 4nd Edition by R. Chabay & B. Sherwood (John Wiley & Sons 2015)

Tutorial & Drill Problems for General Chemistry (and Intro) By Walter S. Hamilton, Ph.D.

Base units of the SI, fundamental constants and modern quantum physics By Christian J Bordé, Published 15 September 2005

SI Units

2017-04-09T22:00:44Z

Dveludhandi6: /* Connectedness */

SI Units

2017-04-09T21:30:33Z

Dveludhandi6: /* A Mathematical Model */

This page is about SI Units. This page is created by Jinyoung Lee. Improved by Ryan Yeung. Claimed by Deepti Veludhandi 2017.
==The Main Idea==

SI unit stands for the 'International System of Units'. It is the modern form of the metric system, and is the most widely used system of measurement. It is used among almost all of the larger countries, with the major exception being the United States. It is used whenever scientific observations or measurements are made. It is made up of 7 standard units. It justifies twenty-two named units, and includes many more unnamed coherent derived units. The system also establishes a set of twenty prefixes to the unit names and unit symbols that may be used when specifying multiples and fractions of the units.

===A Mathematical Model===

There are some mathematical operations required to translate a non-SI unit to SI unit. These are generally simple operations such as addition, subtraction, division, and multiplication. For example <math>{\frac{lb}{2.2}} = kg</math> Since 1 kg(SI unit) is equal to 2.2 lb, to change lb to SI unit, or kg, lb has to be divided by 2.2.

Another example can be length. <math>{\frac{inch}{0.394}} = cm</math> Same method used to change lb to kg. Since 1cm is equal to 0.394inch, inch has to be divided by 0.394 to become SI unit, cm.

These transformations can be done throughout all of the recorded units in the world. In order to preform these simply find the accepted transformation values, and preform a simple division or multiplication operation.

==Base SI units==

[[File:SIbase.jpg]]

This image above shows the base SI units. These units include length, mass, time, electric current, temperature, substance amount, and light intensity. There also exist a variety of other units that are not as commonplace as these other 7.

==Prefix==

Mass, length or any numbers in physics can be very small or very large. Electrons can be a great example. The mass of electron is 0.0000000000000000000000910938356g or 9.10938356 E-31. In SI, prefixes are available to adjust the size of a unit so as to keep the number of those units reasonable. It is kind of difficult to read that number in word. However with the prefix it can be. Image below shows the list of prefixes.

[[File:prefix1.jpg]]

These prefixes are incredibly useful for clarity purposes. The prefixes listed are incredibly useful for a speaker or writer in order to help ease their use.

==Derived SI units==

[[File:Relationdiagram.jpg]]

This image above shows the relationships between many units used in physics based on base SI units. As we can see, most of the units in physics is related to the SI units. It is because there are many quantities that cannot be expressed by a single base SI unit. For example, when talking about the density, it is volume/mass. Mass has it's own SI unit which is a gram. However volume doesn't. Volume is expressed with derived SI unit, meters cubed. As a result, unit for density is <math>\mathrm{m}^3/\mathrm{g}</math> . Those units are called derived SI units. Units can be combined to create new unit. Some frequently-used combinations have their units named. Here are some examples:

*Watt (W), the unit of power.
**<math>\mathrm{W} = \mathrm{J}/\mathrm{s} \ </math>

*Pascal (Pa), the unit of pressure.
**<math>\mathrm{Pa} = \mathrm{N}/\mathrm{m}^2 \ </math>

*Hertz (Hz), the unit of frequency.
**<math>\mathrm{Hz} = 1/\mathrm{s} = \mathrm{s}^{-1} \ </math>

*Newton (N), the unit of force.
**<math>\mathrm{N} = \mathrm{kg} \cdot \mathrm{m}/\mathrm{s}^2 </math>

*Joule (J), the unit of energy.
**<math>\mathrm{J} = \mathrm{N} \cdot \mathrm{m} = \mathrm{kg} \cdot \mathrm{m}^2/\mathrm{s}^2 </math>

*Coulomb (C), the unit of electric charge.
**<math>\mathrm{C} = \mathrm{A} \cdot \mathrm{s} </math>

*Volt (V), the unit of electric potential or voltage.
**<math>\mathrm{V} = \mathrm{J}/\mathrm{C} = \mathrm{W}/\mathrm{A} \ </math>

The list is incredibly useful for measuring quantities that dont have a standard SI unit already in place.

==Connectedness==
This topic can be applied to every aspect of science. When solving the problem, or even when doing a research, every equation and theory is based on SI units. It is a promise between scientists to use the certain units to reduce the errors or misunderstanding. Therefore, it is very important to know the concept of SI units. This topic is connected to not only physics but also every other scientific subjects. In addition, it might not be familiar in United States, but in the most of the countries they use SI units in ordinary life. SI units create a form of standardization throughout the scientific community. This standardization stems from their connection to fundamental constants. These constants are dependent on naturally occurring laws on Earth. As a result, since these units are connected to these constants that are unchanging no matter what location on Earth they're being observed at, this system of measurement is able to achieve a high level of standardization. This establishes a sense of unity and allows scientists to be working on the same page no matter what nationality they are. It's through the use of these units that the community of scientists as a whole that error can be reduced to a minimum and calculations and findings can be standardized across the globe. Si units also allow scientists to reproduce experiments, and record their results in the same form. This allows for more credibility among findings as well. SI units are also very useful for the use of dimensional analysis. Dimensional analysis is the mathematical problem solving method that essentially means that any number expression can be multiplied by another and its inherent value won't be changed. This vital problem solving idea is only possible due to the fact that SI units can be converted to non SI units with incredible ease. SI units create an incredible amount of standardization throughout the scientific community and have been essential for the production of viable and credible scientific results.

==History==

The Metric System was created around the time of the French Revolution and the subsequent deposition of two platinum standards representing the meter and the kilogram, on 22 June 1799, in the Archives de la Republic in Paris can be seen as the first step in the development of the present International System of Units. Each of the base units has root within the physical world. For example the unit of metre is derived from dimensions of the Earth, the kilogram was derived the volume of of one liter of water. These 2 units are the baseline for the remainder of the SI system. The new metric system was originally abandoned by France. In 1837, the metric system was readopted by France, and slowly then became adopted by the scientific community. After this a man named James Clerk Maxwell presented the idea of a number of base units, time, mass, and length. This 3 base units could then be used to derive a series of other measurements throughout the scientific world. However it was quickly discovered that these units cannot describe non-mechanical properties. Most importantly they couldn't properly describe the electrical properties of the world. A man named Giovanni Giorgi, an Italian physicist and electrical engineer, proposed a fourth base unit should be added to the original 3 in order to properly describe the electrical systems of the world. This unit was later decided, in 1935, to be the ampere thus allowing the world to aptly describe electrical systems as well. As the years passed these units began to become more and more commonplace among the world, with many other countries beginning to use the SI system as their main form of measurement. The SI system quickly became the accepted scientific measuring system as well. The use of this system has helped to advance and drive scientific advancement throughout the years.

===Further reading===

SI Units for Clinical Measurement 1st Edition by Donald S. Young

Matter & Interactions, Vol. I: Modern Mechanics, 4nd Edition by R. Chabay & B. Sherwood (John Wiley & Sons 2015)

Base units of the SI, fundamental constants and modern quantum physics by Christian J Bordé

==References==

http://physics.nist.gov/ National institute of standards and Technology.

http://wps.prenhall.com/wps/media/objects/165/169061/blb9ch0104.html Pearson educational site.

Matter & Interactions, Vol. I: Modern Mechanics, 4nd Edition by R. Chabay & B. Sherwood (John Wiley & Sons 2015)

Tutorial & Drill Problems for General Chemistry (and Intro) By Walter S. Hamilton, Ph.D.

Base units of the SI, fundamental constants and modern quantum physics By Christian J Bordé, Published 15 September 2005

SI Units

2017-04-09T21:26:35Z

Dveludhandi6:

This page is about SI Units. This page is created by Jinyoung Lee. Improved by Ryan Yeung. Claimed by Deepti Veludhandi 2017.
==The Main Idea==

SI unit stands for the 'International System of Units'. It is the modern form of the metric system, and is the most widely used system of measurement. It is used among almost all of the larger countries, with the major exception being the United States. It is used whenever scientific observations or measurements are made. It is made up of 7 standard units. It justifies twenty-two named units, and includes many more unnamed coherent derived units. The system also establishes a set of twenty prefixes to the unit names and unit symbols that may be used when specifying multiples and fractions of the units.

===A Mathematical Model===

There are some mathematical operations required to translate a non-SI unit to SI unit. For example <math>{\frac{lb}{2.2}} = kg</math> Since 1 kg(SI unit) is equal to 2.2 lb, to change lb to SI unit, or kg, lb has to be divided by 2.2.

Another example can be length. <math>{\frac{inch}{0.394}} = cm</math> Same method used to change lb to kg. Since 1cm is equal to 0.394inch, inch has to be divided by 0.394 to become SI unit, cm.

These transformations can be done throughout all of the recorded units in the world. In order to preform these simply find the accepted transformation values, and preform a simple division or multiplication operation.

==Base SI units==

[[File:SIbase.jpg]]

This image above shows the base SI units. These units include length, mass, time, electric current, temperature, substance amount, and light intensity. There also exist a variety of other units that are not as commonplace as these other 7.

==Prefix==

Mass, length or any numbers in physics can be very small or very large. Electrons can be a great example. The mass of electron is 0.0000000000000000000000910938356g or 9.10938356 E-31. In SI, prefixes are available to adjust the size of a unit so as to keep the number of those units reasonable. It is kind of difficult to read that number in word. However with the prefix it can be. Image below shows the list of prefixes.

[[File:prefix1.jpg]]

These prefixes are incredibly useful for clarity purposes. The prefixes listed are incredibly useful for a speaker or writer in order to help ease their use.

==Derived SI units==

[[File:Relationdiagram.jpg]]

This image above shows the relationships between many units used in physics based on base SI units. As we can see, most of the units in physics is related to the SI units. It is because there are many quantities that cannot be expressed by a single base SI unit. For example, when talking about the density, it is volume/mass. Mass has it's own SI unit which is a gram. However volume doesn't. Volume is expressed with derived SI unit, meters cubed. As a result, unit for density is <math>\mathrm{m}^3/\mathrm{g}</math> . Those units are called derived SI units. Units can be combined to create new unit. Some frequently-used combinations have their units named. Here are some examples:

*Watt (W), the unit of power.
**<math>\mathrm{W} = \mathrm{J}/\mathrm{s} \ </math>

*Pascal (Pa), the unit of pressure.
**<math>\mathrm{Pa} = \mathrm{N}/\mathrm{m}^2 \ </math>

*Hertz (Hz), the unit of frequency.
**<math>\mathrm{Hz} = 1/\mathrm{s} = \mathrm{s}^{-1} \ </math>

*Newton (N), the unit of force.
**<math>\mathrm{N} = \mathrm{kg} \cdot \mathrm{m}/\mathrm{s}^2 </math>

*Joule (J), the unit of energy.
**<math>\mathrm{J} = \mathrm{N} \cdot \mathrm{m} = \mathrm{kg} \cdot \mathrm{m}^2/\mathrm{s}^2 </math>

*Coulomb (C), the unit of electric charge.
**<math>\mathrm{C} = \mathrm{A} \cdot \mathrm{s} </math>

*Volt (V), the unit of electric potential or voltage.
**<math>\mathrm{V} = \mathrm{J}/\mathrm{C} = \mathrm{W}/\mathrm{A} \ </math>

The list is incredibly useful for measuring quantities that dont have a standard SI unit already in place.

==Connectedness==
This topic can be applied to every aspect of science. When solving the problem, or even when doing a research, every equation and theory is based on SI units. It is a promise between scientists to use the certain units to reduce the errors or misunderstanding. Therefore, it is very important to know the concept of SI units. This topic is connected to not only physics but also every other scientific subjects. In addition, it might not be familiar in United States, but in the most of the countries they use SI units in ordinary life. SI units create a form of standardization throughout the scientific community. This standardization stems from their connection to fundamental constants. These constants are dependent on naturally occurring laws on Earth. As a result, since these units are connected to these constants that are unchanging no matter what location on Earth they're being observed at, this system of measurement is able to achieve a high level of standardization. This establishes a sense of unity and allows scientists to be working on the same page no matter what nationality they are. It's through the use of these units that the community of scientists as a whole that error can be reduced to a minimum and calculations and findings can be standardized across the globe. Si units also allow scientists to reproduce experiments, and record their results in the same form. This allows for more credibility among findings as well. SI units are also very useful for the use of dimensional analysis. Dimensional analysis is the mathematical problem solving method that essentially means that any number expression can be multiplied by another and its inherent value won't be changed. This vital problem solving idea is only possible due to the fact that SI units can be converted to non SI units with incredible ease. SI units create an incredible amount of standardization throughout the scientific community and have been essential for the production of viable and credible scientific results.

==History==

The Metric System was created around the time of the French Revolution and the subsequent deposition of two platinum standards representing the meter and the kilogram, on 22 June 1799, in the Archives de la Republic in Paris can be seen as the first step in the development of the present International System of Units. Each of the base units has root within the physical world. For example the unit of metre is derived from dimensions of the Earth, the kilogram was derived the volume of of one liter of water. These 2 units are the baseline for the remainder of the SI system. The new metric system was originally abandoned by France. In 1837, the metric system was readopted by France, and slowly then became adopted by the scientific community. After this a man named James Clerk Maxwell presented the idea of a number of base units, time, mass, and length. This 3 base units could then be used to derive a series of other measurements throughout the scientific world. However it was quickly discovered that these units cannot describe non-mechanical properties. Most importantly they couldn't properly describe the electrical properties of the world. A man named Giovanni Giorgi, an Italian physicist and electrical engineer, proposed a fourth base unit should be added to the original 3 in order to properly describe the electrical systems of the world. This unit was later decided, in 1935, to be the ampere thus allowing the world to aptly describe electrical systems as well. As the years passed these units began to become more and more commonplace among the world, with many other countries beginning to use the SI system as their main form of measurement. The SI system quickly became the accepted scientific measuring system as well. The use of this system has helped to advance and drive scientific advancement throughout the years.

===Further reading===

SI Units for Clinical Measurement 1st Edition by Donald S. Young

Matter & Interactions, Vol. I: Modern Mechanics, 4nd Edition by R. Chabay & B. Sherwood (John Wiley & Sons 2015)

Base units of the SI, fundamental constants and modern quantum physics by Christian J Bordé

==References==

http://physics.nist.gov/ National institute of standards and Technology.

http://wps.prenhall.com/wps/media/objects/165/169061/blb9ch0104.html Pearson educational site.

Matter & Interactions, Vol. I: Modern Mechanics, 4nd Edition by R. Chabay & B. Sherwood (John Wiley & Sons 2015)

Tutorial & Drill Problems for General Chemistry (and Intro) By Walter S. Hamilton, Ph.D.

Base units of the SI, fundamental constants and modern quantum physics By Christian J Bordé, Published 15 September 2005

SI Units

2017-04-09T21:26:00Z

Dveludhandi6: /* Connectedness */

This page is about SI Units. This page is created by Jinyoung Lee. Improved by Ryan Yeung. Claimed by Deepti Veludhandi.
==The Main Idea==

SI unit stands for the 'International System of Units'. It is the modern form of the metric system, and is the most widely used system of measurement. It is used among almost all of the larger countries, with the major exception being the United States. It is used whenever scientific observations or measurements are made. It is made up of 7 standard units. It justifies twenty-two named units, and includes many more unnamed coherent derived units. The system also establishes a set of twenty prefixes to the unit names and unit symbols that may be used when specifying multiples and fractions of the units.

===A Mathematical Model===

There are some mathematical operations required to translate a non-SI unit to SI unit. For example <math>{\frac{lb}{2.2}} = kg</math> Since 1 kg(SI unit) is equal to 2.2 lb, to change lb to SI unit, or kg, lb has to be divided by 2.2.

Another example can be length. <math>{\frac{inch}{0.394}} = cm</math> Same method used to change lb to kg. Since 1cm is equal to 0.394inch, inch has to be divided by 0.394 to become SI unit, cm.

These transformations can be done throughout all of the recorded units in the world. In order to preform these simply find the accepted transformation values, and preform a simple division or multiplication operation.

==Base SI units==

[[File:SIbase.jpg]]

This image above shows the base SI units. These units include length, mass, time, electric current, temperature, substance amount, and light intensity. There also exist a variety of other units that are not as commonplace as these other 7.

==Prefix==

Mass, length or any numbers in physics can be very small or very large. Electrons can be a great example. The mass of electron is 0.0000000000000000000000910938356g or 9.10938356 E-31. In SI, prefixes are available to adjust the size of a unit so as to keep the number of those units reasonable. It is kind of difficult to read that number in word. However with the prefix it can be. Image below shows the list of prefixes.

[[File:prefix1.jpg]]

These prefixes are incredibly useful for clarity purposes. The prefixes listed are incredibly useful for a speaker or writer in order to help ease their use.

==Derived SI units==

[[File:Relationdiagram.jpg]]

This image above shows the relationships between many units used in physics based on base SI units. As we can see, most of the units in physics is related to the SI units. It is because there are many quantities that cannot be expressed by a single base SI unit. For example, when talking about the density, it is volume/mass. Mass has it's own SI unit which is a gram. However volume doesn't. Volume is expressed with derived SI unit, meters cubed. As a result, unit for density is <math>\mathrm{m}^3/\mathrm{g}</math> . Those units are called derived SI units. Units can be combined to create new unit. Some frequently-used combinations have their units named. Here are some examples:

*Watt (W), the unit of power.
**<math>\mathrm{W} = \mathrm{J}/\mathrm{s} \ </math>

*Pascal (Pa), the unit of pressure.
**<math>\mathrm{Pa} = \mathrm{N}/\mathrm{m}^2 \ </math>

*Hertz (Hz), the unit of frequency.
**<math>\mathrm{Hz} = 1/\mathrm{s} = \mathrm{s}^{-1} \ </math>

*Newton (N), the unit of force.
**<math>\mathrm{N} = \mathrm{kg} \cdot \mathrm{m}/\mathrm{s}^2 </math>

*Joule (J), the unit of energy.
**<math>\mathrm{J} = \mathrm{N} \cdot \mathrm{m} = \mathrm{kg} \cdot \mathrm{m}^2/\mathrm{s}^2 </math>

*Coulomb (C), the unit of electric charge.
**<math>\mathrm{C} = \mathrm{A} \cdot \mathrm{s} </math>

*Volt (V), the unit of electric potential or voltage.
**<math>\mathrm{V} = \mathrm{J}/\mathrm{C} = \mathrm{W}/\mathrm{A} \ </math>

The list is incredibly useful for measuring quantities that dont have a standard SI unit already in place.

==Connectedness==
This topic can be applied to every aspect of science. When solving the problem, or even when doing a research, every equation and theory is based on SI units. It is a promise between scientists to use the certain units to reduce the errors or misunderstanding. Therefore, it is very important to know the concept of SI units. This topic is connected to not only physics but also every other scientific subjects. In addition, it might not be familiar in United States, but in the most of the countries they use SI units in ordinary life. SI units create a form of standardization throughout the scientific community. This standardization stems from their connection to fundamental constants. These constants are dependent on naturally occurring laws on Earth. As a result, since these units are connected to these constants that are unchanging no matter what location on Earth they're being observed at, this system of measurement is able to achieve a high level of standardization. This establishes a sense of unity and allows scientists to be working on the same page no matter what nationality they are. It's through the use of these units that the community of scientists as a whole that error can be reduced to a minimum and calculations and findings can be standardized across the globe. Si units also allow scientists to reproduce experiments, and record their results in the same form. This allows for more credibility among findings as well. SI units are also very useful for the use of dimensional analysis. Dimensional analysis is the mathematical problem solving method that essentially means that any number expression can be multiplied by another and its inherent value won't be changed. This vital problem solving idea is only possible due to the fact that SI units can be converted to non SI units with incredible ease. SI units create an incredible amount of standardization throughout the scientific community and have been essential for the production of viable and credible scientific results.

==History==

The Metric System was created around the time of the French Revolution and the subsequent deposition of two platinum standards representing the meter and the kilogram, on 22 June 1799, in the Archives de la Republic in Paris can be seen as the first step in the development of the present International System of Units. Each of the base units has root within the physical world. For example the unit of metre is derived from dimensions of the Earth, the kilogram was derived the volume of of one liter of water. These 2 units are the baseline for the remainder of the SI system. The new metric system was originally abandoned by France. In 1837, the metric system was readopted by France, and slowly then became adopted by the scientific community. After this a man named James Clerk Maxwell presented the idea of a number of base units, time, mass, and length. This 3 base units could then be used to derive a series of other measurements throughout the scientific world. However it was quickly discovered that these units cannot describe non-mechanical properties. Most importantly they couldn't properly describe the electrical properties of the world. A man named Giovanni Giorgi, an Italian physicist and electrical engineer, proposed a fourth base unit should be added to the original 3 in order to properly describe the electrical systems of the world. This unit was later decided, in 1935, to be the ampere thus allowing the world to aptly describe electrical systems as well. As the years passed these units began to become more and more commonplace among the world, with many other countries beginning to use the SI system as their main form of measurement. The SI system quickly became the accepted scientific measuring system as well. The use of this system has helped to advance and drive scientific advancement throughout the years.

===Further reading===

SI Units for Clinical Measurement 1st Edition by Donald S. Young

Matter & Interactions, Vol. I: Modern Mechanics, 4nd Edition by R. Chabay & B. Sherwood (John Wiley & Sons 2015)

Base units of the SI, fundamental constants and modern quantum physics by Christian J Bordé

==References==

http://physics.nist.gov/ National institute of standards and Technology.

http://wps.prenhall.com/wps/media/objects/165/169061/blb9ch0104.html Pearson educational site.

Matter & Interactions, Vol. I: Modern Mechanics, 4nd Edition by R. Chabay & B. Sherwood (John Wiley & Sons 2015)

Tutorial & Drill Problems for General Chemistry (and Intro) By Walter S. Hamilton, Ph.D.

Base units of the SI, fundamental constants and modern quantum physics By Christian J Bordé, Published 15 September 2005

SI Units

2017-04-09T20:51:42Z

Dveludhandi6: /* References */

This page is about SI Units. This page is created by Jinyoung Lee. Improved by Ryan Yeung. Claimed by Deepti Veludhandi.
==The Main Idea==

SI unit stands for the 'International System of Units'. It is the modern form of the metric system, and is the most widely used system of measurement. It is used among almost all of the larger countries, with the major exception being the United States. It is used whenever scientific observations or measurements are made. It is made up of 7 standard units. It justifies twenty-two named units, and includes many more unnamed coherent derived units. The system also establishes a set of twenty prefixes to the unit names and unit symbols that may be used when specifying multiples and fractions of the units.

===A Mathematical Model===

There are some mathematical operations required to translate a non-SI unit to SI unit. For example <math>{\frac{lb}{2.2}} = kg</math> Since 1 kg(SI unit) is equal to 2.2 lb, to change lb to SI unit, or kg, lb has to be divided by 2.2.

Another example can be length. <math>{\frac{inch}{0.394}} = cm</math> Same method used to change lb to kg. Since 1cm is equal to 0.394inch, inch has to be divided by 0.394 to become SI unit, cm.

These transformations can be done throughout all of the recorded units in the world. In order to preform these simply find the accepted transformation values, and preform a simple division or multiplication operation.

==Base SI units==

[[File:SIbase.jpg]]

This image above shows the base SI units. These units include length, mass, time, electric current, temperature, substance amount, and light intensity. There also exist a variety of other units that are not as commonplace as these other 7.

==Prefix==

Mass, length or any numbers in physics can be very small or very large. Electrons can be a great example. The mass of electron is 0.0000000000000000000000910938356g or 9.10938356 E-31. In SI, prefixes are available to adjust the size of a unit so as to keep the number of those units reasonable. It is kind of difficult to read that number in word. However with the prefix it can be. Image below shows the list of prefixes.

[[File:prefix1.jpg]]

These prefixes are incredibly useful for clarity purposes. The prefixes listed are incredibly useful for a speaker or writer in order to help ease their use.

==Derived SI units==

[[File:Relationdiagram.jpg]]

This image above shows the relationships between many units used in physics based on base SI units. As we can see, most of the units in physics is related to the SI units. It is because there are many quantities that cannot be expressed by a single base SI unit. For example, when talking about the density, it is volume/mass. Mass has it's own SI unit which is a gram. However volume doesn't. Volume is expressed with derived SI unit, meters cubed. As a result, unit for density is <math>\mathrm{m}^3/\mathrm{g}</math> . Those units are called derived SI units. Units can be combined to create new unit. Some frequently-used combinations have their units named. Here are some examples:

*Watt (W), the unit of power.
**<math>\mathrm{W} = \mathrm{J}/\mathrm{s} \ </math>

*Pascal (Pa), the unit of pressure.
**<math>\mathrm{Pa} = \mathrm{N}/\mathrm{m}^2 \ </math>

*Hertz (Hz), the unit of frequency.
**<math>\mathrm{Hz} = 1/\mathrm{s} = \mathrm{s}^{-1} \ </math>

*Newton (N), the unit of force.
**<math>\mathrm{N} = \mathrm{kg} \cdot \mathrm{m}/\mathrm{s}^2 </math>

*Joule (J), the unit of energy.
**<math>\mathrm{J} = \mathrm{N} \cdot \mathrm{m} = \mathrm{kg} \cdot \mathrm{m}^2/\mathrm{s}^2 </math>

*Coulomb (C), the unit of electric charge.
**<math>\mathrm{C} = \mathrm{A} \cdot \mathrm{s} </math>

*Volt (V), the unit of electric potential or voltage.
**<math>\mathrm{V} = \mathrm{J}/\mathrm{C} = \mathrm{W}/\mathrm{A} \ </math>

The list is incredibly useful for measuring quantities that dont have a standard SI unit already in place.

==Connectedness==
This topic can be applied to every aspect of science. When solving the problem, or even when doing a research, every equation and theory is based on SI units. It is a promise between scientists to use the certain units to reduce the errors or misunderstanding. Therefore, it is very important to know the concept of SI units. This topic is connected to not only physics but also every other scientific subjects. In addition, it might not be familiar in United States, but in the most of the countries they use SI units in ordinary life. SI units create a form of standardization throughout the scientific community. It's through the use of these units that the community of scientists as a whole that error can be reduced to a minimum and calculations and findings can be standardized across the globe. Si units also allow scientists to reproduce experiments, and record their results in the same form. This allows for more credibility among findings as well. SI units are also very useful for the use of dimensional analysis. Dimensional analysis is the mathematical problem solving method that essentially means that any number expression can be multiplied by another and its inherent value won't be changed. This vital problem solving idea is only possible due to the fact that SI units can be converted to non SI units with incredible ease. SI units create an incredible amount of standardization throughout the scientific community and have been essential for the production of viable and credible scientific results.

==History==

The Metric System was created around the time of the French Revolution and the subsequent deposition of two platinum standards representing the meter and the kilogram, on 22 June 1799, in the Archives de la Republic in Paris can be seen as the first step in the development of the present International System of Units. Each of the base units has root within the physical world. For example the unit of metre is derived from dimensions of the Earth, the kilogram was derived the volume of of one liter of water. These 2 units are the baseline for the remainder of the SI system. The new metric system was originally abandoned by France. In 1837, the metric system was readopted by France, and slowly then became adopted by the scientific community. After this a man named James Clerk Maxwell presented the idea of a number of base units, time, mass, and length. This 3 base units could then be used to derive a series of other measurements throughout the scientific world. However it was quickly discovered that these units cannot describe non-mechanical properties. Most importantly they couldn't properly describe the electrical properties of the world. A man named Giovanni Giorgi, an Italian physicist and electrical engineer, proposed a fourth base unit should be added to the original 3 in order to properly describe the electrical systems of the world. This unit was later decided, in 1935, to be the ampere thus allowing the world to aptly describe electrical systems as well. As the years passed these units began to become more and more commonplace among the world, with many other countries beginning to use the SI system as their main form of measurement. The SI system quickly became the accepted scientific measuring system as well. The use of this system has helped to advance and drive scientific advancement throughout the years.

===Further reading===

SI Units for Clinical Measurement 1st Edition by Donald S. Young

Matter & Interactions, Vol. I: Modern Mechanics, 4nd Edition by R. Chabay & B. Sherwood (John Wiley & Sons 2015)

Base units of the SI, fundamental constants and modern quantum physics by Christian J Bordé

==References==

http://physics.nist.gov/ National institute of standards and Technology.

http://wps.prenhall.com/wps/media/objects/165/169061/blb9ch0104.html Pearson educational site.

Matter & Interactions, Vol. I: Modern Mechanics, 4nd Edition by R. Chabay & B. Sherwood (John Wiley & Sons 2015)

Tutorial & Drill Problems for General Chemistry (and Intro) By Walter S. Hamilton, Ph.D.

Base units of the SI, fundamental constants and modern quantum physics By Christian J Bordé, Published 15 September 2005

SI Units

2017-04-09T20:50:30Z

Dveludhandi6: /* Further reading */

This page is about SI Units. This page is created by Jinyoung Lee. Improved by Ryan Yeung. Claimed by Deepti Veludhandi.
==The Main Idea==

SI unit stands for the 'International System of Units'. It is the modern form of the metric system, and is the most widely used system of measurement. It is used among almost all of the larger countries, with the major exception being the United States. It is used whenever scientific observations or measurements are made. It is made up of 7 standard units. It justifies twenty-two named units, and includes many more unnamed coherent derived units. The system also establishes a set of twenty prefixes to the unit names and unit symbols that may be used when specifying multiples and fractions of the units.

===A Mathematical Model===

There are some mathematical operations required to translate a non-SI unit to SI unit. For example <math>{\frac{lb}{2.2}} = kg</math> Since 1 kg(SI unit) is equal to 2.2 lb, to change lb to SI unit, or kg, lb has to be divided by 2.2.

Another example can be length. <math>{\frac{inch}{0.394}} = cm</math> Same method used to change lb to kg. Since 1cm is equal to 0.394inch, inch has to be divided by 0.394 to become SI unit, cm.

These transformations can be done throughout all of the recorded units in the world. In order to preform these simply find the accepted transformation values, and preform a simple division or multiplication operation.

==Base SI units==

[[File:SIbase.jpg]]

This image above shows the base SI units. These units include length, mass, time, electric current, temperature, substance amount, and light intensity. There also exist a variety of other units that are not as commonplace as these other 7.

==Prefix==

Mass, length or any numbers in physics can be very small or very large. Electrons can be a great example. The mass of electron is 0.0000000000000000000000910938356g or 9.10938356 E-31. In SI, prefixes are available to adjust the size of a unit so as to keep the number of those units reasonable. It is kind of difficult to read that number in word. However with the prefix it can be. Image below shows the list of prefixes.

[[File:prefix1.jpg]]

These prefixes are incredibly useful for clarity purposes. The prefixes listed are incredibly useful for a speaker or writer in order to help ease their use.

==Derived SI units==

[[File:Relationdiagram.jpg]]

This image above shows the relationships between many units used in physics based on base SI units. As we can see, most of the units in physics is related to the SI units. It is because there are many quantities that cannot be expressed by a single base SI unit. For example, when talking about the density, it is volume/mass. Mass has it's own SI unit which is a gram. However volume doesn't. Volume is expressed with derived SI unit, meters cubed. As a result, unit for density is <math>\mathrm{m}^3/\mathrm{g}</math> . Those units are called derived SI units. Units can be combined to create new unit. Some frequently-used combinations have their units named. Here are some examples:

*Watt (W), the unit of power.
**<math>\mathrm{W} = \mathrm{J}/\mathrm{s} \ </math>

*Pascal (Pa), the unit of pressure.
**<math>\mathrm{Pa} = \mathrm{N}/\mathrm{m}^2 \ </math>

*Hertz (Hz), the unit of frequency.
**<math>\mathrm{Hz} = 1/\mathrm{s} = \mathrm{s}^{-1} \ </math>

*Newton (N), the unit of force.
**<math>\mathrm{N} = \mathrm{kg} \cdot \mathrm{m}/\mathrm{s}^2 </math>

*Joule (J), the unit of energy.
**<math>\mathrm{J} = \mathrm{N} \cdot \mathrm{m} = \mathrm{kg} \cdot \mathrm{m}^2/\mathrm{s}^2 </math>

*Coulomb (C), the unit of electric charge.
**<math>\mathrm{C} = \mathrm{A} \cdot \mathrm{s} </math>

*Volt (V), the unit of electric potential or voltage.
**<math>\mathrm{V} = \mathrm{J}/\mathrm{C} = \mathrm{W}/\mathrm{A} \ </math>

The list is incredibly useful for measuring quantities that dont have a standard SI unit already in place.

==Connectedness==
This topic can be applied to every aspect of science. When solving the problem, or even when doing a research, every equation and theory is based on SI units. It is a promise between scientists to use the certain units to reduce the errors or misunderstanding. Therefore, it is very important to know the concept of SI units. This topic is connected to not only physics but also every other scientific subjects. In addition, it might not be familiar in United States, but in the most of the countries they use SI units in ordinary life. SI units create a form of standardization throughout the scientific community. It's through the use of these units that the community of scientists as a whole that error can be reduced to a minimum and calculations and findings can be standardized across the globe. Si units also allow scientists to reproduce experiments, and record their results in the same form. This allows for more credibility among findings as well. SI units are also very useful for the use of dimensional analysis. Dimensional analysis is the mathematical problem solving method that essentially means that any number expression can be multiplied by another and its inherent value won't be changed. This vital problem solving idea is only possible due to the fact that SI units can be converted to non SI units with incredible ease. SI units create an incredible amount of standardization throughout the scientific community and have been essential for the production of viable and credible scientific results.

==History==

The Metric System was created around the time of the French Revolution and the subsequent deposition of two platinum standards representing the meter and the kilogram, on 22 June 1799, in the Archives de la Republic in Paris can be seen as the first step in the development of the present International System of Units. Each of the base units has root within the physical world. For example the unit of metre is derived from dimensions of the Earth, the kilogram was derived the volume of of one liter of water. These 2 units are the baseline for the remainder of the SI system. The new metric system was originally abandoned by France. In 1837, the metric system was readopted by France, and slowly then became adopted by the scientific community. After this a man named James Clerk Maxwell presented the idea of a number of base units, time, mass, and length. This 3 base units could then be used to derive a series of other measurements throughout the scientific world. However it was quickly discovered that these units cannot describe non-mechanical properties. Most importantly they couldn't properly describe the electrical properties of the world. A man named Giovanni Giorgi, an Italian physicist and electrical engineer, proposed a fourth base unit should be added to the original 3 in order to properly describe the electrical systems of the world. This unit was later decided, in 1935, to be the ampere thus allowing the world to aptly describe electrical systems as well. As the years passed these units began to become more and more commonplace among the world, with many other countries beginning to use the SI system as their main form of measurement. The SI system quickly became the accepted scientific measuring system as well. The use of this system has helped to advance and drive scientific advancement throughout the years.

===Further reading===

SI Units for Clinical Measurement 1st Edition by Donald S. Young

Matter & Interactions, Vol. I: Modern Mechanics, 4nd Edition by R. Chabay & B. Sherwood (John Wiley & Sons 2015)

Base units of the SI, fundamental constants and modern quantum physics by Christian J Bordé

==References==

http://physics.nist.gov/ National institute of standards and Technology.

http://wps.prenhall.com/wps/media/objects/165/169061/blb9ch0104.html Pearson educational site.

Matter & Interactions, Vol. I: Modern Mechanics, 4nd Edition by R. Chabay & B. Sherwood (John Wiley & Sons 2015)

Tutorial & Drill Problems for General Chemistry (and Intro) By Walter S. Hamilton, Ph.D.

SI Units

2017-04-09T20:45:31Z

Dveludhandi6:

This page is about SI Units. This page is created by Jinyoung Lee. Improved by Ryan Yeung. Claimed by Deepti Veludhandi.
==The Main Idea==

SI unit stands for the 'International System of Units'. It is the modern form of the metric system, and is the most widely used system of measurement. It is used among almost all of the larger countries, with the major exception being the United States. It is used whenever scientific observations or measurements are made. It is made up of 7 standard units. It justifies twenty-two named units, and includes many more unnamed coherent derived units. The system also establishes a set of twenty prefixes to the unit names and unit symbols that may be used when specifying multiples and fractions of the units.

===A Mathematical Model===

There are some mathematical operations required to translate a non-SI unit to SI unit. For example <math>{\frac{lb}{2.2}} = kg</math> Since 1 kg(SI unit) is equal to 2.2 lb, to change lb to SI unit, or kg, lb has to be divided by 2.2.

Another example can be length. <math>{\frac{inch}{0.394}} = cm</math> Same method used to change lb to kg. Since 1cm is equal to 0.394inch, inch has to be divided by 0.394 to become SI unit, cm.

These transformations can be done throughout all of the recorded units in the world. In order to preform these simply find the accepted transformation values, and preform a simple division or multiplication operation.

==Base SI units==

[[File:SIbase.jpg]]

This image above shows the base SI units. These units include length, mass, time, electric current, temperature, substance amount, and light intensity. There also exist a variety of other units that are not as commonplace as these other 7.

==Prefix==

Mass, length or any numbers in physics can be very small or very large. Electrons can be a great example. The mass of electron is 0.0000000000000000000000910938356g or 9.10938356 E-31. In SI, prefixes are available to adjust the size of a unit so as to keep the number of those units reasonable. It is kind of difficult to read that number in word. However with the prefix it can be. Image below shows the list of prefixes.

[[File:prefix1.jpg]]

These prefixes are incredibly useful for clarity purposes. The prefixes listed are incredibly useful for a speaker or writer in order to help ease their use.

==Derived SI units==

[[File:Relationdiagram.jpg]]

This image above shows the relationships between many units used in physics based on base SI units. As we can see, most of the units in physics is related to the SI units. It is because there are many quantities that cannot be expressed by a single base SI unit. For example, when talking about the density, it is volume/mass. Mass has it's own SI unit which is a gram. However volume doesn't. Volume is expressed with derived SI unit, meters cubed. As a result, unit for density is <math>\mathrm{m}^3/\mathrm{g}</math> . Those units are called derived SI units. Units can be combined to create new unit. Some frequently-used combinations have their units named. Here are some examples:

*Watt (W), the unit of power.
**<math>\mathrm{W} = \mathrm{J}/\mathrm{s} \ </math>

*Pascal (Pa), the unit of pressure.
**<math>\mathrm{Pa} = \mathrm{N}/\mathrm{m}^2 \ </math>

*Hertz (Hz), the unit of frequency.
**<math>\mathrm{Hz} = 1/\mathrm{s} = \mathrm{s}^{-1} \ </math>

*Newton (N), the unit of force.
**<math>\mathrm{N} = \mathrm{kg} \cdot \mathrm{m}/\mathrm{s}^2 </math>

*Joule (J), the unit of energy.
**<math>\mathrm{J} = \mathrm{N} \cdot \mathrm{m} = \mathrm{kg} \cdot \mathrm{m}^2/\mathrm{s}^2 </math>

*Coulomb (C), the unit of electric charge.
**<math>\mathrm{C} = \mathrm{A} \cdot \mathrm{s} </math>

*Volt (V), the unit of electric potential or voltage.
**<math>\mathrm{V} = \mathrm{J}/\mathrm{C} = \mathrm{W}/\mathrm{A} \ </math>

The list is incredibly useful for measuring quantities that dont have a standard SI unit already in place.

==Connectedness==
This topic can be applied to every aspect of science. When solving the problem, or even when doing a research, every equation and theory is based on SI units. It is a promise between scientists to use the certain units to reduce the errors or misunderstanding. Therefore, it is very important to know the concept of SI units. This topic is connected to not only physics but also every other scientific subjects. In addition, it might not be familiar in United States, but in the most of the countries they use SI units in ordinary life. SI units create a form of standardization throughout the scientific community. It's through the use of these units that the community of scientists as a whole that error can be reduced to a minimum and calculations and findings can be standardized across the globe. Si units also allow scientists to reproduce experiments, and record their results in the same form. This allows for more credibility among findings as well. SI units are also very useful for the use of dimensional analysis. Dimensional analysis is the mathematical problem solving method that essentially means that any number expression can be multiplied by another and its inherent value won't be changed. This vital problem solving idea is only possible due to the fact that SI units can be converted to non SI units with incredible ease. SI units create an incredible amount of standardization throughout the scientific community and have been essential for the production of viable and credible scientific results.

==History==

The Metric System was created around the time of the French Revolution and the subsequent deposition of two platinum standards representing the meter and the kilogram, on 22 June 1799, in the Archives de la Republic in Paris can be seen as the first step in the development of the present International System of Units. Each of the base units has root within the physical world. For example the unit of metre is derived from dimensions of the Earth, the kilogram was derived the volume of of one liter of water. These 2 units are the baseline for the remainder of the SI system. The new metric system was originally abandoned by France. In 1837, the metric system was readopted by France, and slowly then became adopted by the scientific community. After this a man named James Clerk Maxwell presented the idea of a number of base units, time, mass, and length. This 3 base units could then be used to derive a series of other measurements throughout the scientific world. However it was quickly discovered that these units cannot describe non-mechanical properties. Most importantly they couldn't properly describe the electrical properties of the world. A man named Giovanni Giorgi, an Italian physicist and electrical engineer, proposed a fourth base unit should be added to the original 3 in order to properly describe the electrical systems of the world. This unit was later decided, in 1935, to be the ampere thus allowing the world to aptly describe electrical systems as well. As the years passed these units began to become more and more commonplace among the world, with many other countries beginning to use the SI system as their main form of measurement. The SI system quickly became the accepted scientific measuring system as well. The use of this system has helped to advance and drive scientific advancement throughout the years.

===Further reading===

SI Units for Clinical Measurement 1st Edition by Donald S. Young

Matter & Interactions, Vol. I: Modern Mechanics, 4nd Edition by R. Chabay & B. Sherwood (John Wiley & Sons 2015)

==References==

http://physics.nist.gov/ National institute of standards and Technology.

http://wps.prenhall.com/wps/media/objects/165/169061/blb9ch0104.html Pearson educational site.

Matter & Interactions, Vol. I: Modern Mechanics, 4nd Edition by R. Chabay & B. Sherwood (John Wiley & Sons 2015)

Tutorial & Drill Problems for General Chemistry (and Intro) By Walter S. Hamilton, Ph.D.