Physics Book - User contributions [en]

Electric Force

2016-11-25T22:06:29Z

Sboyce7:

--[[User:Asaxon7|Asaxon7]] ([[User talk:Asaxon7|talk]]) 00:48, 18 November 2015 (EST) Claimed by Alayna Saxon

Samuel Boyce (sboyce7) Fall 2016: added increased detail, images, video, example 3, connectedness, references, and other small improvements

This page contains information on the electric force on a point charge. Electric force is created by an external [[Electric Field]], and the strength of this electrical interaction is a vector quantity that has magnitude and direction. If the electric field at a particular location is known, then this field can be used to calculate the electric force of the particle being acted upon. The electric force is directly proportional to the amount of charge within each particle being acted upon by the other's electric field. Moreover, the magnitude of the force is inversely proportional to the square distance between the two interacting particles. It is important to remember that a particle cannot have an electric force on itself; there must be at least two interacting, charged components.

==The Main Idea==
===A Mathematical Model===
The Coulomb Force Law
The formula for the magnitude of the electric force between two point charges is:

<math>F=\frac{1}{4 \pi \epsilon_0 } \frac{|{q}_{1}{q}_{2}|}{r^2} </math>

where '''<math>{q}_{1}</math>''' and '''<math>{q}_{2}</math>''' are the magnitudes of charge of point 1 and point 2 and '''<math>r</math>''' is the distance between the two point charges. The units for electric force are in Newtons. The expression <math>\frac{1}{4 \pi \epsilon_0 }</math> is known as the electric constant and carries the value 9e9. Epsilon 0 defines electric permittivity of space.

Interestingly enough, one can see a relationship between this formula and the formula for gravitational force (<math>F={G} \frac{|{m}_{1}{m}_{2}|}{r^2} </math>). From this relationship, one can conclude that the interactions of two objects as a result of their charges or masses follow similar fundamental laws of physics.

'''Derivations of Electric Force'''

The electric force on a particle can also be written as:

<math>\vec F=q\vec E </math>

where '''<math>q</math>''' is the charge of the particle and '''<math>\vec E </math>''' is the external electric field.

This formula can be derived from <math>|\vec F|=\frac{1}{4 \pi \epsilon_0 } \frac{|{q}_{1}{q}_{2}|}{r^2} </math>, the electric force between two point charges. The magnitude of the electric field created by a point charge is <math>|\vec E|=\frac{1}{4 \pi \epsilon_0 } \frac{|q|}{r^2} </math>, where '''<math>q</math>''' is the magnitude of the charge of the particle and '''<math>r</math>''' is the distance between the observation location and the point charge. Therefore, the magnitude of electric force between point charge 1 and point charge 2 can be written as:

<math>|\vec F|=\frac{1}{4 \pi \epsilon_0 } \frac{|{q}_{1}{q}_{2}|}{r^2}=|{q}_{2}|\frac{1}{4 \pi \epsilon_0 } \frac{|{q}_{1}|}{r^2}=|{q}_{2}||\vec{E}_{1}| </math>

The units of charge are in Coulombs and the units for electric field are in Newton/Coulombs, so this derivation is correct in its dimensions since multiplying the two units gives just Newtons. The Newton is the unit for electric force.

===A Computational Model===
Direction of the Electric Force

The electric force is along a straight line between the two point charges in the observed system. If the point charges have the same sign (i.e. both are either positively or negatively charged), then the charges repel each other. If the signs of the point charges are different (i.e. one is positively charged and one is negatively charged), then the point charges are attracted to each other. The electric force vector acts either in the same or opposite direction of the electric field acting on a particle, depending on the charge of that particle. Remember that negative charges attract, so the electric field of a negative charge will act from the observation location towards the charged negatively charged particle. If the observation particle is positively charged, then the electric force will act in the same direction as the electric field. If the observation particle is negatively charged, then the force will act in the opposite direction as the electric field. The same concepts apply to positive electric fields, which point away from the source location at the observation location.

[[File:WhatisAnElectricForce.png]]

Electric force follows Newton's third law of equal and opposite forces, meaning that the electric force experienced by one of the two interacting objects will be equal and opposite to the electric force of the first object.
==Examples==

===Simple===
'''Problem: '''Find the electric force of a -3 C particle in a region with an electric field of <math><7, 5, 0></math>N/C.

'''Step 1: '''Substitute values into the correct formula.

<math>\vec F=q\vec E </math>

<math>\vec F=(-3 C)<7, 5, 0></math>N/C

<math>\vec F=<-21, -15, 0></math>N

The electric force vector for this particle is <math><-21, -15, 0></math>N.

===Middling===
'''Problem: '''Find the magnitude of electric force on two charged particles located at <math> <0, 0, 0></math>m and <math> <0, 10, 0></math>m. The first particle has a charge of +5 nC and the second particle has a charge of -10 nC. Is the force attractive or repulsive?

'''Step 1: '''Find the distance between the two point charges.

<math>d=\sqrt{(0 m-0 m)^2+(0 m-10 m)^2+(0 m-0 m)^2}=\sqrt{100 m}=10 </math>m.

The distance between the two points is 10 m.

'''Step 2: '''Substitute values into the correct formula.

<math>|\vec F|=\frac{1}{4 \pi \epsilon_0 } \frac{|{q}_{1}{q}_{2}|}{r^2}=\frac{1}{4 \pi \epsilon_0 } \frac{|(5 nC)(-10 nC)|}{(10m)^2} </math>

<math>|\vec F|=4.5e-9 </math> N

The magnitude of electric force is <math>|\vec F|=4.5e-9 </math> N.

'''Step 3: '''Determine if force is attractive or repulsive.

Since the first particle is positively charged and the second is negatively charged, the force is attractive. The particles are attracted to each other.

===Difficult===
Problem:
[[File:SpringTest1Prob1.png]]

Given the above graphic, find A) The net force acting on particle -q' and B) The direction of the net force on this charge.

A) Net Force
[[File:T1P1A.png]]

B) Direction of the net force
[[File:T1P1B.png]]

Problems involving electric force exclusively will not be more complicated than the above. However, the the electric force can be used in calculation of a net force acting on a particle in combination with non-Coulomb electric force and magnetic force.

==Connectedness==

Electric force is ubiquitous in everyday life, although it is not always evident. One common example of electric force is the attraction of clothes to one another after being washed. Clearly, the charges caused by the machine-drying process create opposite, attractive charges on different pieces of clothing which cause them to stick together. Thinking more complexly, the electric force is also prevalent in almost all forms of modern technology involving electricity. One particular example is the process of charging a smartphone: the electric force allows a current to be generated which transfers charge from outlets to the internal battery of these devices. A more whimsical example of the electric force in real life involves charging a balloon by rubbing it against one's hair then observing it stick to a wall due to the transfer of charge, covered in a later section of this book. A final, slightly more complicated example of the electric force is seen in the production of abrasive paper, whereby positively charged-smoothing particles are attracted to a negatively charged, smooth surface to create papers like sandpaper.

[[File:abrasive.jpg]]

As a civil engineering major, electric force is not directly related to my major. However, in the area of structural civil engineering, the electric force is likely observed between different materials used to construct objects or in the tools used in construction. One potential example of relativity (although a slight stretch) is the usage of abrasive paper in construction, which in itself is formed due to the effects of the electric force.

==History==

French physicist Charles-Augustin de Coulomb discovered in 1785 that the magnitude of electric force between two charged particles is directly proportional to the product of the absolute value of the two charges and inversely proportional to the distance squared between the two particles. He experimented with a torsion balance which consisted of an insulated bar suspended in the air by a silk thread. Coulomb attached a metal ball with a known charge to one end of the insulated bar. He then brought another ball with the same charge near the first ball. This distance between the two balls was recorded. The balls repelled each other, causing the silk thread to twist. The angle of the twist was measured and by knowing how much force was required for the thread to twist through the recorded angle, Coulomb was able to calculate the force between the two balls and derive the formula for electric force.

The following video explains Coulomb's experiment and the corresponding derivation of his law.
[[Media:https://www.youtube.com/watch?v=FYSTGX-F1GM]]

== See Also ==

Electric Field: [http://www.physicsbook.gatech.edu/Electric_Field]

Net Force: [http://www.physicsbook.gatech.edu/Lorentz_Force]

==References==

Matter & Interactions, Vol. II: Electric and Magnetic Interactions, 4th Edition

https://en.wikipedia.org/wiki/Coulomb's_law

http://hyperphysics.phy-astr.gsu.edu/hbase/electric/elefor.html

http://www.jfinternational.com/ph/coulomb-law.html

'''Images'''
Electric Force Direction: http://blog.omninox.org/what-is-an-electric-force-2/

[[Category:Forces]]

File:Abrasive.jpg

2016-11-25T21:49:06Z

Sboyce7: abrasive paper from lowe's

abrasive paper from lowe's

Electric Force

2016-11-25T21:48:34Z

Sboyce7:

--[[User:Asaxon7|Asaxon7]] ([[User talk:Asaxon7|talk]]) 00:48, 18 November 2015 (EST) Claimed by Alayna Saxon

claimed for editing and additional examples- Samuel Boyce Fall 2016

This page contains information on the electric force on a point charge. Electric force is created by an external [[Electric Field]], and the strength of this electrical interaction is a vector quantity that has magnitude and direction. If the electric field at a particular location is known, then this field can be used to calculate the electric force of the particle being acted upon. The electric force is directly proportional to the amount of charge within each particle being acted upon by the other's electric field. Moreover, the magnitude of the force is inversely proportional to the square distance between the two interacting particles. It is important to remember that a particle cannot have an electric force on itself; there must be at least two interacting, charged components.

==The Main Idea==
===A Mathematical Model===
The Coulomb Force Law
The formula for the magnitude of the electric force between two point charges is:

<math>F=\frac{1}{4 \pi \epsilon_0 } \frac{|{q}_{1}{q}_{2}|}{r^2} </math>

where '''<math>{q}_{1}</math>''' and '''<math>{q}_{2}</math>''' are the magnitudes of charge of point 1 and point 2 and '''<math>r</math>''' is the distance between the two point charges. The units for electric force are in Newtons. The expression <math>\frac{1}{4 \pi \epsilon_0 }</math> is known as the electric constant and carries the value 9e9.

Interestingly enough, one can see a relationship between this formula and the formula for gravitational force (<math>F={G} \frac{|{m}_{1}{m}_{2}|}{r^2} </math>). From this relationship, one can conclude that the interactions of two objects as a result of their charges or masses follow similar fundamental laws of physics.

'''Derivations of Electric Force'''

The electric force on a particle can also be written as:

<math>\vec F=q\vec E </math>

where '''<math>q</math>''' is the charge of the particle and '''<math>\vec E </math>''' is the external electric field.

This formula can be derived from <math>|\vec F|=\frac{1}{4 \pi \epsilon_0 } \frac{|{q}_{1}{q}_{2}|}{r^2} </math>, the electric force between two point charges. The magnitude of the electric field created by a point charge is <math>|\vec E|=\frac{1}{4 \pi \epsilon_0 } \frac{|q|}{r^2} </math>, where '''<math>q</math>''' is the magnitude of the charge of the particle and '''<math>r</math>''' is the distance between the observation location and the point charge. Therefore, the magnitude of electric force between point charge 1 and point charge 2 can be written as:

<math>|\vec F|=\frac{1}{4 \pi \epsilon_0 } \frac{|{q}_{1}{q}_{2}|}{r^2}=|{q}_{2}|\frac{1}{4 \pi \epsilon_0 } \frac{|{q}_{1}|}{r^2}=|{q}_{2}||\vec{E}_{1}| </math>

The units of charge are in Coulombs and the units for electric field are in Newton/Coulombs, so this derivation is correct in its dimensions since multiplying the two units gives just Newtons. The Newton is the unit for electric force.

===A Computational Model===
Direction of the Electric Force
The electric force is along a straight line between the two point charges in the observed system. If the point charges have the same sign (i.e. both are either positively or negatively charged), then the charges repel each other. If the signs of the point charges are different (i.e. one is positively charged and one is negatively charged), then the point charges are attracted to each other. The electric force vector acts either in the same or opposite direction of the electric field acting on a particle, depending on the charge of that particle. Remember that negative charges attract, so the electric field of a negative charge will act from the observation location towards the charged negatively charged particle. If the observation particle is positively charged, then the electric force will act in the same direction as the electric field. If the observation particle is negatively charged, then the force will act in the opposite direction as the electric field. The same concepts apply to positive electric fields, which point away from the source location at the observation location.

[[File:WhatisAnElectricForce.png]]

==Examples==

===Simple===
'''Problem: '''Find the electric force of a -3 C particle in a region with an electric field of <math><7, 5, 0></math>N/C.

'''Step 1: '''Substitute values into the correct formula.

<math>\vec F=q\vec E </math>

<math>\vec F=(-3 C)<7, 5, 0></math>N/C

<math>\vec F=<-21, -15, 0></math>N

The electric force vector for this particle is <math><-21, -15, 0></math>N.

===Middling===
'''Problem: '''Find the magnitude of electric force on two charged particles located at <math> <0, 0, 0></math>m and <math> <0, 10, 0></math>m. The first particle has a charge of +5 nC and the second particle has a charge of -10 nC. Is the force attractive or repulsive?

'''Step 1: '''Find the distance between the two point charges.

<math>d=\sqrt{(0 m-0 m)^2+(0 m-10 m)^2+(0 m-0 m)^2}=\sqrt{100 m}=10 </math>m.

The distance between the two points is 10 m.

'''Step 2: '''Substitute values into the correct formula.

<math>|\vec F|=\frac{1}{4 \pi \epsilon_0 } \frac{|{q}_{1}{q}_{2}|}{r^2}=\frac{1}{4 \pi \epsilon_0 } \frac{|(5 nC)(-10 nC)|}{(10m)^2} </math>

<math>|\vec F|=4.5e-9 </math> N

The magnitude of electric force is <math>|\vec F|=4.5e-9 </math> N.

'''Step 3: '''Determine if force is attractive or repulsive.

Since the first particle is positively charged and the second is negatively charged, the force is attractive. The particles are attracted to each other.

===Difficult===
Problem:
[[File:SpringTest1Prob1.png]]

Given the above graphic, find A) The net force acting on particle -q' and B) The direction of the net force on this charge.

A) Net Force
[[File:T1P1A.png]]

B) Direction of the net force
[[File:T1P1B.png]]

Problems involving electric force exclusively will not be more complicated than the above. However, the the electric force can be used in calculation of a net force acting on a particle in combination with non-Coulomb electric force and magnetic force.

==Connectedness==

Electric force is ubiquitous in everyday life, although it is not always evident. One common example of electric force is the attraction of clothes to one another after being washed. Clearly, the charges caused by the machine-drying process create opposite, attractive charges on different pieces of clothing which cause them to stick together. Thinking more complexly, the electric force is also prevalent in almost all forms of modern technology involving electricity. One particular example is the process of charging a smartphone: the electric force allows a current to be generated which transfers charge from outlets to the internal battery of these devices. A more whimsical example of the electric force in real life involves charging a balloon by rubbing it against one's hair then observing it stick to a wall due to the transfer of charge, covered in a later section of this book. A final, slightly more complicated example of the electric force is seen in the production of abrasive paper, whereby positively charged-smoothing particles are attracted to a negatively charged, smooth surface to create papers like sandpaper.

[[File:abrasive.jpg]]

As a civil engineering major, electric force is not directly related to my major. However, in the area of structural civil engineering, the electric force is likely observed between different materials used to construct objects or in the tools used in construction. One potential example of relativity (although a slight stretch) is the usage of abrasive paper in construction, which in itself is formed due to the effects of the electric force.

==History==

French physicist Charles-Augustin de Coulomb discovered in 1785 that the magnitude of electric force between two charged particles is directly proportional to the product of the absolute value of the two charges and inversely proportional to the distance squared between the two particles. He experimented with a torsion balance which consisted of an insulated bar suspended in the air by a silk thread. Coulomb attached a metal ball with a known charge to one end of the insulated bar. He then brought another ball with the same charge near the first ball. This distance between the two balls was recorded. The balls repelled each other, causing the silk thread to twist. The angle of the twist was measured and by knowing how much force was required for the thread to twist through the recorded angle, Coulomb was able to calculate the force between the two balls and derive the formula for electric force.

The following video explains Coulomb's experiment and the corresponding derivation of his law.
[[Media:https://www.youtube.com/watch?v=FYSTGX-F1GM]]

== See also ==

===External links===

http://www.physicsclassroom.com/class/estatics/Lesson-3/Coulomb-s-Law

http://www.springtownisd.net/cms/lib3/TX21000442/Centricity/domain/156/notes/Electric%20and%20magnetic%20forces%20in%20everyday%20life.pdf

==References==

Matter & Interactions, Vol. II: Electric and Magnetic Interactions, 4th Edition

https://en.wikipedia.org/wiki/Coulomb's_law

=Images=
Electric Force Direction: http://blog.omninox.org/what-is-an-electric-force-2/

[[Category:Which Category did you place this in?]]

File:T1P1B.png

2016-11-25T21:23:21Z

Sboyce7: Spring 2015 test 1 problem 1 part b from t-square

Spring 2015 test 1 problem 1 part b from t-square

File:T1P1A.png

2016-11-25T21:22:56Z

Sboyce7: Spring 2015 test 1 problem 1 part a from t-square

Spring 2015 test 1 problem 1 part a from t-square

Electric Force

2016-11-25T21:22:17Z

Sboyce7:

--[[User:Asaxon7|Asaxon7]] ([[User talk:Asaxon7|talk]]) 00:48, 18 November 2015 (EST) Claimed by Alayna Saxon

claimed for editing and additional examples- Samuel Boyce Fall 2016

This page contains information on the electric force on a point charge. Electric force is created by an external [[Electric Field]], and the strength of this electrical interaction is a vector quantity that has magnitude and direction. If the electric field at a particular location is known, then this field can be used to calculate the electric force of the particle being acted upon. The electric force is directly proportional to the amount of charge within each particle being acted upon by the other's electric field. Moreover, the magnitude of the force is inversely proportional to the square distance between the two interacting particles. It is important to remember that a particle cannot have an electric force on itself; there must be at least two interacting, charged components.

==The Main Idea==
===A Mathematical Model===
The Coulomb Force Law
The formula for the magnitude of the electric force between two point charges is:

<math>F=\frac{1}{4 \pi \epsilon_0 } \frac{|{q}_{1}{q}_{2}|}{r^2} </math>

where '''<math>{q}_{1}</math>''' and '''<math>{q}_{2}</math>''' are the magnitudes of charge of point 1 and point 2 and '''<math>r</math>''' is the distance between the two point charges. The units for electric force are in Newtons. The expression <math>\frac{1}{4 \pi \epsilon_0 }</math> is known as the electric constant and carries the value 9e9.

Interestingly enough, one can see a relationship between this formula and the formula for gravitational force (<math>F={G} \frac{|{m}_{1}{m}_{2}|}{r^2} </math>). From this relationship, one can conclude that the interactions of two objects as a result of their charges or masses follow similar fundamental laws of physics.

'''Derivations of Electric Force'''

The electric force on a particle can also be written as:

<math>\vec F=q\vec E </math>

where '''<math>q</math>''' is the charge of the particle and '''<math>\vec E </math>''' is the external electric field.

This formula can be derived from <math>|\vec F|=\frac{1}{4 \pi \epsilon_0 } \frac{|{q}_{1}{q}_{2}|}{r^2} </math>, the electric force between two point charges. The magnitude of the electric field created by a point charge is <math>|\vec E|=\frac{1}{4 \pi \epsilon_0 } \frac{|q|}{r^2} </math>, where '''<math>q</math>''' is the magnitude of the charge of the particle and '''<math>r</math>''' is the distance between the observation location and the point charge. Therefore, the magnitude of electric force between point charge 1 and point charge 2 can be written as:

<math>|\vec F|=\frac{1}{4 \pi \epsilon_0 } \frac{|{q}_{1}{q}_{2}|}{r^2}=|{q}_{2}|\frac{1}{4 \pi \epsilon_0 } \frac{|{q}_{1}|}{r^2}=|{q}_{2}||\vec{E}_{1}| </math>

The units of charge are in Coulombs and the units for electric field are in Newton/Coulombs, so this derivation is correct in its dimensions since multiplying the two units gives just Newtons. The Newton is the unit for electric force.

===A Computational Model===
Direction of the Electric Force
The electric force is along a straight line between the two point charges in the observed system. If the point charges have the same sign (i.e. both are either positively or negatively charged), then the charges repel each other. If the signs of the point charges are different (i.e. one is positively charged and one is negatively charged), then the point charges are attracted to each other. The electric force vector acts either in the same or opposite direction of the electric field acting on a particle, depending on the charge of that particle. Remember that negative charges attract, so the electric field of a negative charge will act from the observation location towards the charged negatively charged particle. If the observation particle is positively charged, then the electric force will act in the same direction as the electric field. If the observation particle is negatively charged, then the force will act in the opposite direction as the electric field. The same concepts apply to positive electric fields, which point away from the source location at the observation location.

[[File:WhatisAnElectricForce.png]]

==Examples==

===Simple===
'''Problem: '''Find the electric force of a -3 C particle in a region with an electric field of <math><7, 5, 0></math>N/C.

'''Step 1: '''Substitute values into the correct formula.

<math>\vec F=q\vec E </math>

<math>\vec F=(-3 C)<7, 5, 0></math>N/C

<math>\vec F=<-21, -15, 0></math>N

The electric force vector for this particle is <math><-21, -15, 0></math>N.

===Middling===
'''Problem: '''Find the magnitude of electric force on two charged particles located at <math> <0, 0, 0></math>m and <math> <0, 10, 0></math>m. The first particle has a charge of +5 nC and the second particle has a charge of -10 nC. Is the force attractive or repulsive?

'''Step 1: '''Find the distance between the two point charges.

<math>d=\sqrt{(0 m-0 m)^2+(0 m-10 m)^2+(0 m-0 m)^2}=\sqrt{100 m}=10 </math>m.

The distance between the two points is 10 m.

'''Step 2: '''Substitute values into the correct formula.

<math>|\vec F|=\frac{1}{4 \pi \epsilon_0 } \frac{|{q}_{1}{q}_{2}|}{r^2}=\frac{1}{4 \pi \epsilon_0 } \frac{|(5 nC)(-10 nC)|}{(10m)^2} </math>

<math>|\vec F|=4.5e-9 </math> N

The magnitude of electric force is <math>|\vec F|=4.5e-9 </math> N.

'''Step 3: '''Determine if force is attractive or repulsive.

Since the first particle is positively charged and the second is negatively charged, the force is attractive. The particles are attracted to each other.

===Difficult===
Problem:
[[File:SpringTest1Prob1.png]]

Given the above graphic, find A) The net force acting on particle -q' and B) The direction of the net force on this charge.

A) Net Force
[[File:T1P1A.png]]

B)
[[File:T1P1B.png]]

==Connectedness==

==History==

French physicist Charles-Augustin de Coulomb discovered in 1785 that the magnitude of electric force between two charged particles is directly proportional to the product of the absolute value of the two charges and inversely proportional to the distance squared between the two particles. He experimented with a torsion balance which consisted of an insulated bar suspended in the air by a silk thread. Coulomb attached a metal ball with a known charge to one end of the insulated bar. He then brought another ball with the same charge near the first ball. This distance between the two balls was recorded. The balls repelled each other, causing the silk thread to twist. The angle of the twist was measured and by knowing how much force was required for the thread to twist through the recorded angle, Coulomb was able to calculate the force between the two balls and derive the formula for electric force.

== See also ==

===External links===

http://www.physicsclassroom.com/class/estatics/Lesson-3/Coulomb-s-Law

==References==

Matter & Interactions, Vol. II: Electric and Magnetic Interactions, 4th Edition

https://en.wikipedia.org/wiki/Coulomb's_law

=Images=
Electric Force Direction: http://blog.omninox.org/what-is-an-electric-force-2/

[[Category:Which Category did you place this in?]]

File:SpringTest1Prob1.png

2016-11-25T21:17:39Z

Sboyce7: Taken from T-Square: Spring 2015 Test 1, Problem 1

Taken from T-Square: Spring 2015 Test 1, Problem 1

Electric Force

2016-11-25T21:17:03Z

Sboyce7:

--[[User:Asaxon7|Asaxon7]] ([[User talk:Asaxon7|talk]]) 00:48, 18 November 2015 (EST) Claimed by Alayna Saxon

claimed for editing and additional examples- Samuel Boyce Fall 2016

This page contains information on the electric force on a point charge. Electric force is created by an external [[Electric Field]], and the strength of this electrical interaction is a vector quantity that has magnitude and direction. If the electric field at a particular location is known, then this field can be used to calculate the electric force of the particle being acted upon. The electric force is directly proportional to the amount of charge within each particle being acted upon by the other's electric field. Moreover, the magnitude of the force is inversely proportional to the square distance between the two interacting particles. It is important to remember that a particle cannot have an electric force on itself; there must be at least two interacting, charged components.

==The Main Idea==
===A Mathematical Model===
The Coulomb Force Law
The formula for the magnitude of the electric force between two point charges is:

<math>F=\frac{1}{4 \pi \epsilon_0 } \frac{|{q}_{1}{q}_{2}|}{r^2} </math>

where '''<math>{q}_{1}</math>''' and '''<math>{q}_{2}</math>''' are the magnitudes of charge of point 1 and point 2 and '''<math>r</math>''' is the distance between the two point charges. The units for electric force are in Newtons. The expression <math>\frac{1}{4 \pi \epsilon_0 }</math> is known as the electric constant and carries the value 9e9.

Interestingly enough, one can see a relationship between this formula and the formula for gravitational force (<math>F={G} \frac{|{m}_{1}{m}_{2}|}{r^2} </math>). From this relationship, one can conclude that the interactions of two objects as a result of their charges or masses follow similar fundamental laws of physics.

'''Derivations of Electric Force'''

The electric force on a particle can also be written as:

<math>\vec F=q\vec E </math>

where '''<math>q</math>''' is the charge of the particle and '''<math>\vec E </math>''' is the external electric field.

This formula can be derived from <math>|\vec F|=\frac{1}{4 \pi \epsilon_0 } \frac{|{q}_{1}{q}_{2}|}{r^2} </math>, the electric force between two point charges. The magnitude of the electric field created by a point charge is <math>|\vec E|=\frac{1}{4 \pi \epsilon_0 } \frac{|q|}{r^2} </math>, where '''<math>q</math>''' is the magnitude of the charge of the particle and '''<math>r</math>''' is the distance between the observation location and the point charge. Therefore, the magnitude of electric force between point charge 1 and point charge 2 can be written as:

<math>|\vec F|=\frac{1}{4 \pi \epsilon_0 } \frac{|{q}_{1}{q}_{2}|}{r^2}=|{q}_{2}|\frac{1}{4 \pi \epsilon_0 } \frac{|{q}_{1}|}{r^2}=|{q}_{2}||\vec{E}_{1}| </math>

The units of charge are in Coulombs and the units for electric field are in Newton/Coulombs, so this derivation is correct in its dimensions since multiplying the two units gives just Newtons. The Newton is the unit for electric force.

===A Computational Model===
Direction of the Electric Force
The electric force is along a straight line between the two point charges in the observed system. If the point charges have the same sign (i.e. both are either positively or negatively charged), then the charges repel each other. If the signs of the point charges are different (i.e. one is positively charged and one is negatively charged), then the point charges are attracted to each other. The electric force vector acts either in the same or opposite direction of the electric field acting on a particle, depending on the charge of that particle. Remember that negative charges attract, so the electric field of a negative charge will act from the observation location towards the charged negatively charged particle. If the observation particle is positively charged, then the electric force will act in the same direction as the electric field. If the observation particle is negatively charged, then the force will act in the opposite direction as the electric field. The same concepts apply to positive electric fields, which point away from the source location at the observation location.

[[File:WhatisAnElectricForce.png]]

==Examples==

===Simple===
'''Problem: '''Find the electric force of a -3 C particle in a region with an electric field of <math><7, 5, 0></math>N/C.

'''Step 1: '''Substitute values into the correct formula.

<math>\vec F=q\vec E </math>

<math>\vec F=(-3 C)<7, 5, 0></math>N/C

<math>\vec F=<-21, -15, 0></math>N

The electric force vector for this particle is <math><-21, -15, 0></math>N.

===Middling===
'''Problem: '''Find the magnitude of electric force on two charged particles located at <math> <0, 0, 0></math>m and <math> <0, 10, 0></math>m. The first particle has a charge of +5 nC and the second particle has a charge of -10 nC. Is the force attractive or repulsive?

'''Step 1: '''Find the distance between the two point charges.

<math>d=\sqrt{(0 m-0 m)^2+(0 m-10 m)^2+(0 m-0 m)^2}=\sqrt{100 m}=10 </math>m.

The distance between the two points is 10 m.

'''Step 2: '''Substitute values into the correct formula.

<math>|\vec F|=\frac{1}{4 \pi \epsilon_0 } \frac{|{q}_{1}{q}_{2}|}{r^2}=\frac{1}{4 \pi \epsilon_0 } \frac{|(5 nC)(-10 nC)|}{(10m)^2} </math>

<math>|\vec F|=4.5e-9 </math> N

The magnitude of electric force is <math>|\vec F|=4.5e-9 </math> N.

'''Step 3: '''Determine if force is attractive or repulsive.

Since the first particle is positively charged and the second is negatively charged, the force is attractive. The particles are attracted to each other.

===Difficult===
Problem:
[[File:SpringTest1Prob1.png]]
==Connectedness==

==History==

French physicist Charles-Augustin de Coulomb discovered in 1785 that the magnitude of electric force between two charged particles is directly proportional to the product of the absolute value of the two charges and inversely proportional to the distance squared between the two particles. He experimented with a torsion balance which consisted of an insulated bar suspended in the air by a silk thread. Coulomb attached a metal ball with a known charge to one end of the insulated bar. He then brought another ball with the same charge near the first ball. This distance between the two balls was recorded. The balls repelled each other, causing the silk thread to twist. The angle of the twist was measured and by knowing how much force was required for the thread to twist through the recorded angle, Coulomb was able to calculate the force between the two balls and derive the formula for electric force.

== See also ==

===External links===

http://www.physicsclassroom.com/class/estatics/Lesson-3/Coulomb-s-Law

==References==

Matter & Interactions, Vol. II: Electric and Magnetic Interactions, 4th Edition

https://en.wikipedia.org/wiki/Coulomb's_law

=Images=
Electric Force Direction: http://blog.omninox.org/what-is-an-electric-force-2/

[[Category:Which Category did you place this in?]]

Electric Force

2016-11-25T20:43:57Z

Sboyce7:

--[[User:Asaxon7|Asaxon7]] ([[User talk:Asaxon7|talk]]) 00:48, 18 November 2015 (EST) Claimed by Alayna Saxon

claimed for editing and additional examples- Samuel Boyce Fall 2016

This page contains information on the electric force on a point charge. Electric force is created by an external [[Electric Field]], and the strength of this electrical interaction is a vector quantity that has magnitude and direction. If the electric field at a particular location is known, then this field can be used to calculate the electric force of the particle being acted upon. The electric force is directly proportional to the amount of charge within each particle being acted upon by the other's electric field. Moreover, the magnitude of the force is inversely proportional to the square distance between the two interacting particles. It is important to remember that a particle cannot have an electric force on itself; there must be at least two interacting, charged components.

==The Coulomb Force Law==

The formula for the magnitude of the electric force between two point charges is:

<math>F=\frac{1}{4 \pi \epsilon_0 } \frac{|{q}_{1}{q}_{2}|}{r^2} </math>

where '''<math>{q}_{1}</math>''' and '''<math>{q}_{2}</math>''' are the magnitudes of charge of point 1 and point 2 and '''<math>r</math>''' is the distance between the two point charges. The units for electric force are in Newtons. The expression <math>\frac{1}{4 \pi \epsilon_0 }</math> is known as the electric constant and carries the value 9e9.

Interestingly enough, one can see a relationship between this formula and the formula for gravitational force (<math>F={G} \frac{|{m}_{1}{m}_{2}|}{r^2} </math>). From this relationship, one can conclude that the interactions of two objects as a result of their charges or masses follow similar fundamental laws of physics.

===Direction of Electric Force===

The electric force is along a straight line between the two point charges in the observed system. If the point charges have the same sign (i.e. both are either positively or negatively charged), then the charges repel each other. If the signs of the point charges are different (i.e. one is positively charged and one is negatively charged), then the point charges are attracted to each other. The electric force vector acts either in the same or opposite direction of the electric field acting on a particle, depending on the charge of that particle. Remember that negative charges attract, so the electric field of a negative charge will act from the observation location towards the charged negatively charged particle. If the observation particle is positively charged, then the electric force will act in the same direction as the electric field. If the observation particle is negatively charged, then the force will act in the opposite direction as the electric field. The same concepts apply to positive electric fields, which point away from the source location at the observation location.

[[File:WhatisAnElectricForce.png]]

===Derivations of Electric Force===

The electric force on a particle can also be written as:

<math>\vec F=q\vec E </math>

where '''<math>q</math>''' is the charge of the particle and '''<math>\vec E </math>''' is the external electric field.

This formula can be derived from <math>|\vec F|=\frac{1}{4 \pi \epsilon_0 } \frac{|{q}_{1}{q}_{2}|}{r^2} </math>, the electric force between two point charges. The magnitude of the electric field created by a point charge is <math>|\vec E|=\frac{1}{4 \pi \epsilon_0 } \frac{|q|}{r^2} </math>, where '''<math>q</math>''' is the magnitude of the charge of the particle and '''<math>r</math>''' is the distance between the observation location and the point charge. Therefore, the magnitude of electric force between point charge 1 and point charge 2 can be written as:

<math>|\vec F|=\frac{1}{4 \pi \epsilon_0 } \frac{|{q}_{1}{q}_{2}|}{r^2}=|{q}_{2}|\frac{1}{4 \pi \epsilon_0 } \frac{|{q}_{1}|}{r^2}=|{q}_{2}||\vec{E}_{1}| </math>

The units of charge are in Coulombs and the units for electric field are in Newton/Coulombs, so this derivation is correct in its dimensions since multiplying the two units gives just Newtons. The Newton is the unit for electric force.

==A Computational Model==

==Examples==

===Example 1===

'''Problem: '''Find the magnitude of electric force on two charged particles located at <math> <0, 0, 0></math>m and <math> <0, 10, 0></math>m. The first particle has a charge of +5 nC and the second particle has a charge of -10 nC. Is the force attractive or repulsive?

'''Step 1: '''Find the distance between the two point charges.

<math>d=\sqrt{(0 m-0 m)^2+(0 m-10 m)^2+(0 m-0 m)^2}=\sqrt{100 m}=10 </math>m.

The distance between the two points is 10 m.

'''Step 2: '''Substitute values into the correct formula.

<math>|\vec F|=\frac{1}{4 \pi \epsilon_0 } \frac{|{q}_{1}{q}_{2}|}{r^2}=\frac{1}{4 \pi \epsilon_0 } \frac{|(5 nC)(-10 nC)|}{(10m)^2} </math>

<math>|\vec F|=4.5e-9 </math> N

The magnitude of electric force is <math>|\vec F|=4.5e-9 </math> N.

'''Step 3: '''Determine if force is attractive or repulsive.

Since the first particle is positively charged and the second is negatively charged, the force is attractive. The particles are attracted to each other.

===Example 2===

'''Problem: '''Find the electric force of a -3 C particle in a region with an electric field of <math><7, 5, 0></math>N/C.

'''Step 1: '''Substitute values into the correct formula.

<math>\vec F=q\vec E </math>

<math>\vec F=(-3 C)<7, 5, 0></math>N/C

<math>\vec F=<-21, -15, 0></math>N

The electric force vector for this particle is <math><-21, -15, 0></math>N.

===Example 3===

==Connectedness==

==History==

French physicist Charles-Augustin de Coulomb discovered in 1785 that the magnitude of electric force between two charged particles is directly proportional to the product of the absolute value of the two charges and inversely proportional to the distance squared between the two particles. He experimented with a torsion balance which consisted of an insulated bar suspended in the air by a silk thread. Coulomb attached a metal ball with a known charge to one end of the insulated bar. He then brought another ball with the same charge near the first ball. This distance between the two balls was recorded. The balls repelled each other, causing the silk thread to twist. The angle of the twist was measured and by knowing how much force was required for the thread to twist through the recorded angle, Coulomb was able to calculate the force between the two balls and derive the formula for electric force.

== See also ==

===External links===

http://www.physicsclassroom.com/class/estatics/Lesson-3/Coulomb-s-Law

==References==

Matter & Interactions, Vol. II: Electric and Magnetic Interactions, 4th Edition

https://en.wikipedia.org/wiki/Coulomb's_law

[[Category:Which Category did you place this in?]]

File:WhatisAnElectricForce.png

2016-11-25T20:42:56Z

Sboyce7: Effects of the electric force. Retrieved from http://blog.omninox.org/what-is-an-electric-force-2/

Effects of the electric force.

Retrieved from http://blog.omninox.org/what-is-an-electric-force-2/

Electric Force

2016-11-25T20:23:29Z

Sboyce7:

Electric Force

2016-11-25T03:06:56Z

Sboyce7:

Charge Transfer

2016-11-25T03:06:45Z

Sboyce7:

claimed by Lzhang375

If a charged conductor comes in contact, or is in close enough proximity, with another conductor, it is possible to transfer this charge to the second conductor. This process is called '''charge transfer'''. Charges cannot be created or destroyed; this is known as the ''Law of Conservation of Charge''. Therefore, in the transfer of charge between two objects, the amount of charge gained by one object is equal to the amount of charge loss by the other. There are multiple ways that charge can be transferred such as through direct contact and through inductance.

==Insulators vs Conductors==

In an '''insulator''', electrons are bounded tightly to atoms, which prevents charged particles from moving through the material. If charge is transferred to an insulator at a given location, the charge will remain at the location that the transfer occurred.

[[File:inschargedist.gif|thumb|180px|Charges transferred to an insulator remains at the location of transfer.]]

On the other hand, electrons are able to flow freely from particle to particle within '''conductors'''. When charge is transferred to a conductor, the charge is distributed evenly across the surface of the object via ''electron movement''. The electrons will be distributed until the repelling force between the excess electrons is minimized. This is the main difference between insulators and conductors: insulators do not have mobile charged particles whereas conductors have mobile charged particles that allow for charge transfer through the free movement of electrons. Examples of insulators include rubber and air and examples of conductors include metals and salt water.

==Transfer Charges by Conduction==

Electrons move from one object to another (especially with metals) through points of contact. An example of this is rubbing a glass rod with silk. The glass rod will become positively charged and the silk will become negatively charged; this means that electrons were transferred from the glass rod to the silk, since protons are not removed from the nuclei. Rubbing two objects together is not necessary for charge transfer, but because rubbing creates more points of contact between two objects, it facilitates charge transfer.

[[File:Conductiontransfer.gif]]

==Transfer Charges by Induction==

Unlike the transfer of charges by conduction, objects that becomes charged to each other do not require points of contact. When an object is charged, it has an electric field. This electric field will repel or attract electrons in another object. This electron movement is called transfer of charges by induction. A neutral object can be charged by another charged object through a process called '''polarization'''. This is when electrons in the object is repelled or attracted to one side of the object by the charged second object. For example, if a negatively charged sphere is placed near a neutral sphere, the electrons in the neutral sphere will be repelled by the charged sphere. The neutral sphere is now polarized, with one side of it being negatively charged and the other side being positively charged. The negatively charged side of the sphere can be removed through grounding or with a conductor. Once removed, the originally neutral sphere will now be positively charged. Another example of induction is the balloon and black pepper experiment. A balloon can be given a negative charge by rubbing it on hair. When the balloon is placed near grounded black pepper, the black pepper particles will be polarized so that it becomes positively charged on top and will be attracted to the negatively charged balloon.

[[File:Indtransfer.gif]]

== See also ==

http://www.physicsbook.gatech.edu/Charge_Motion_in_Metals

http://www.physicsbook.gatech.edu/Polarization

==References==

Internet resources on this topic:

http://www.physicsclassroom.com/class/estatics/Lesson-1/Conductors-and-Insulators

http://www.physicsclassroom.com/class/estatics/Lesson-1/Charge-Interactions

Chabay, Ruth W., Bruce Sherwood. Matter and Interactions, Volume II: Electric and Magnetic Interactions, 4th Edition. Wiley, 19/2015. VitalBook file.

[[Category:Which Category did you place this in?]]

Main Page

2016-11-25T02:56:06Z

Sboyce7: /* Moving charges, electron current, and conventional current */

__NOTOC__
= '''Georgia Tech Student Wiki for Introductory Physics.''' =

This resource was created so that students can contribute and curate content to help those with limited or no access to a textbook. When reading this website, please correct any errors you may come across. If you read something that isn't clear, please consider revising it for future students!

Looking to make a contribution?
#Pick one of the topics from intro physics listed below
#Add content to that topic or improve the quality of what is already there.
#Need to make a new topic? Edit this page and add it to the list under the appropriate category. Then copy and paste the default [[Template]] into your new page and start editing.

Please remember that this is not a textbook and you are not limited to expressing your ideas with only text and equations. Whenever possible embed: pictures, videos, diagrams, simulations, computational models (e.g. Glowscript), and whatever content you think makes learning physics easier for other students.

== Source Material ==
All of the content added to this resource must be in the public domain or similar free resource. If you are unsure about a source, contact the original author for permission. That said, there is a surprisingly large amount of introductory physics content scattered across the web. Here is an incomplete list of intro physics resources (please update as needed).
* A physics resource written by experts for an expert audience [https://en.wikipedia.org/wiki/Portal:Physics Physics Portal]
* A wiki written for students by a physics expert [http://p3server.pa.msu.edu/coursewiki/doku.php?id=183_notes MSU Physics Wiki]
* A wiki book on modern physics [https://en.wikibooks.org/wiki/Modern_Physics Modern Physics Wiki]
* The MIT open courseware for intro physics [http://ocw.mit.edu/resources/res-8-002-a-wikitextbook-for-introductory-mechanics-fall-2009/index.htm MITOCW Wiki]
* An online concept map of intro physics [http://hyperphysics.phy-astr.gsu.edu/hbase/hph.html HyperPhysics]
* Interactive physics simulations [https://phet.colorado.edu/en/simulations/category/physics PhET]
* OpenStax algebra based intro physics textbook [https://openstaxcollege.org/textbooks/college-physics College Physics]
* The Open Source Physics project is a collection of online physics resources [http://www.opensourcephysics.org/ OSP]
* A resource guide compiled by the [http://www.aapt.org/ AAPT] for educators [http://www.compadre.org/ ComPADRE]

== Resources ==
* Commonly used wiki commands [https://en.wikipedia.org/wiki/Help:Cheatsheet Wiki Cheatsheet]
* A guide to representing equations in math mode [https://en.wikipedia.org/wiki/Help:Displaying_a_formula Wiki Math Mode]
* A page to keep track of all the physics [[Constants]]
* A page for review of [[Vectors]] and vector operations
* A listing of [[Notable Scientist]] with links to their individual pages

<div style="float:left; width:30%; padding:1%;">
==Physics 1==
===Week 1===
<div class="toccolours mw-collapsible mw-collapsed">
====Help with VPython====
<div class="mw-collapsible-content">
*[[VPython]]
*[[VPython basics]]
*[[VPython Common Errors and Troubleshooting]]
*[[VPython Functions]]
*[[VPython Lists]]
*[[VPython Loops]]
*[[VPython Multithreading]]
*[[VPython Animation]]
*[[VPython Objects]]
*[[VPython 3D Objects]]
*[[VPython Reference]]
*[[VPython MapReduceFilter]]
*[[VPython GUIs]]
</div>
</div>

<div class="toccolours mw-collapsible mw-collapsed">

====Vectors and Units====
edit: Maria Furukawa
<div class="mw-collapsible-content">
*[[Vectors]]
*[[SI Units]]
</div>
</div>

<div class="toccolours mw-collapsible mw-collapsed">

====Interactions====
<div class="mw-collapsible-content">
*[[Types of Interactions and How to Detect Them]]
</div>
</div>

<div class="toccolours mw-collapsible mw-collapsed">
====Velocity and Momentum====
<div class="mw-collapsible-content">
*[[Newton's First Law of Motion]]
*[[Velocity]]
*[[Mass]]
*[[Speed and Velocity]]
*[[Relative Velocity]]
*[[Derivation of Average Velocity]]
*[[2-Dimensional Motion]]
*[[3-Dimensional Position and Motion]]
</div>
</div>

===Week 2===
<div class="toccolours mw-collapsible mw-collapsed">
====Momentum and the Momentum Principle====
<div class="mw-collapsible-content">
*[[Momentum Principle]]
*[[Inertia]]
*[[Net Force]]
*[[Derivation of the Momentum Principle]]
*[[Impulse Momentum]]
*[[Acceleration]]
*[[Momentum with respect to external Forces]]
</div>
</div>

<div class="toccolours mw-collapsible mw-collapsed">
====Iterative Prediction with a Constant Force====
<div class="mw-collapsible-content">
*[[Newton’s Second Law of Motion]]
*[[Iterative Prediction]]
*[[Kinematics]]
*[[Newton’s Laws and Linear Momentum]]
*[[Projectile Motion]]
</div>
</div>

===Week 3===
<div class="toccolours mw-collapsible mw-collapsed">
====Analytic Prediction with a Constant Force====
<div class="mw-collapsible-content">
*[[Analytical Prediction]]
</div>
</div>

<div class="toccolours mw-collapsible mw-collapsed">
====Iterative Prediction with a Varying Force====
<div class="mw-collapsible-content">
*[[Predicting Change in multiple dimensions]]
*[[Spring Force]]
*[[Hooke's Law]]
*[[Simple Harmonic Motion]]
*[[Iterative Prediction of Spring-Mass System]]
*[[Terminal Speed]]
*[[Determinism]]
</div>
</div>

===Week 4===
<div class="toccolours mw-collapsible mw-collapsed">
====Fundamental Interactions====
<div class="mw-collapsible-content">
*[[Gravitational Force]]
*[[Electric Force]]
*[[Reciprocity]]
</div>
</div>

===Week 5===
<div class="toccolours mw-collapsible mw-collapsed">
====Conservation of Momentum====
<div class="mw-collapsible-content">
*[[Conservation of Momentum]]
</div>
</div>
<div class="toccolours mw-collapsible mw-collapsed">

====Properties of Matter====
<div class="mw-collapsible-content">
*[[Kinds of Matter]]
*[[Ball and Spring Model of Matter]]
*[[Density]]
*[[Length and Stiffness of an Interatomic Bond]]
*[[Young's Modulus]]
*[[Speed of Sound in Solids]]
*[[Malleability]]
*[[Ductility]]
*[[Weight]]
*[[Hardness]]
*[[Boiling Point]]
*[[Melting Point]]
</div>
</div>

===Week 6===
<div class="toccolours mw-collapsible mw-collapsed">
====Identifying Forces====
<div class="mw-collapsible-content">
*[[Free Body Diagram]]
Claimed by pg66
*[[Compression or Normal Force]]
*[[Tension]]
</div>
</div>
<div class="toccolours mw-collapsible mw-collapsed">

====Curving Motion====
<div class="mw-collapsible-content">
*[[Curving Motion]]
*[[Centripetal Force and Curving Motion]]
*[[Perpetual Freefall (Orbit)]]
</div>
</div>

===Week 7===
<div class="toccolours mw-collapsible mw-collapsed">
====Energy Principle====
<div class="mw-collapsible-content">
*[[The Energy Principle]]
*[[Conservation of Energy]]
*[[Kinetic Energy]]
*[[Work]]
*[[Power (Mechanical)]]
</div>
</div>

===Week 8===
<div class="toccolours mw-collapsible mw-collapsed">
====Work by Non-Constant Forces====
<div class="mw-collapsible-content">
*[[Work Done By A Nonconstant Force]]
</div>
</div>
<div class="toccolours mw-collapsible mw-collapsed">
====Potential Energy====
<div class="mw-collapsible-content">
*[[Potential Energy]]
*[[Potential Energy of Macroscopic Springs]]
*[[Spring Potential Energy]]
*[[Ball and Spring Model]]
*[[Gravitational Potential Energy]]
*[[Energy Graphs]]
*[[Escape Velocity]]
</div>
</div>

===Week 9===
<div class="toccolours mw-collapsible mw-collapsed">
====Multiparticle Systems====
<div class="mw-collapsible-content">
*[[Center of Mass]]
*[[Multi-particle analysis of Momentum]]
*[[Momentum with respect to external Forces]]
*[[Potential Energy of a Multiparticle System]]
*[[Work and Energy for an Extended System]]
*[[Internal Energy]]
**[[Potential Energy of a Pair of Neutral Atoms]]
</div>
</div>

===Week 10===
<div class="toccolours mw-collapsible mw-collapsed">
====Choice of System====
<div class="mw-collapsible-content">
*[[System & Surroundings]]
</div>
</div>
<div class="toccolours mw-collapsible mw-collapsed">
====Thermal Energy, Dissipation and Transfer of Energy====
<div class="mw-collapsible-content">
*[[Thermal Energy]]
*[[Specific Heat]]
*[[Heat Capacity]]
*[[Specific Heat Capacity]]
*[[First Law of Thermodynamics]]
*[[Second Law of Thermodynamics and Entropy]]
*[[Temperature]]
*[[Predicting Change]]
*[[Energy Transfer due to a Temperature Difference]]
*[[Transformation of Energy]]
*[[The Maxwell-Boltzmann Distribution]]
*[[Air Resistance]]
</div>
</div>
<div class="toccolours mw-collapsible mw-collapsed">
====Rotational and Vibrational Energy====
<div class="mw-collapsible-content">
*[[Translational, Rotational and Vibrational Energy]]
</div>
</div>

===Week 11===
<div class="toccolours mw-collapsible mw-collapsed">
====Different Models of a System====
<div class="mw-collapsible-content">
*[[Point Particle Systems]]
*[[Real Systems]]
</div>
</div>
<div class="toccolours mw-collapsible mw-collapsed">
====Models of Friction====
<div class="mw-collapsible-content">
*[[Friction]]
*[[Static Friction]]
</div>
</div>

===Week 12===
<div class="toccolours mw-collapsible mw-collapsed">
====Collisions====
<div class="mw-collapsible-content">
*[[Newton's Third Law of Motion]]
*[[Collisions]]
*[[Elastic Collisions]]
*[[Inelastic Collisions]]
*[[Maximally Inelastic Collision]]
*[[Head-on Collision of Equal Masses]]
*[[Head-on Collision of Unequal Masses]]
*[[Scattering: Collisions in 2D and 3D]]
*[[Rutherford Experiment and Atomic Collisions]]
*[[Coefficient of Restitution]]
</div>
</div>

===Week 13===
<div class="toccolours mw-collapsible mw-collapsed">
====Rotations====
<div class="mw-collapsible-content">
*[[Rotation]]
*[[Angular Velocity]]
*[[Eulerian Angles]]
</div>
</div>
<div class="toccolours mw-collapsible mw-collapsed">
====Angular Momentum====
<div class="mw-collapsible-content">
*[[Total Angular Momentum]]
*[[Translational Angular Momentum]]
*[[Rotational Angular Momentum]]
*[[The Angular Momentum Principle]]
*[[Angular Momentum Compared to Linear Momentum]]
*[[Angular Impulse]]
*[[Predicting the Position of a Rotating System]]
*[[Angular Momentum of Multiparticle Systems]]
*[[The Moments of Inertia]]
*[[Moment of Inertia for a cylinder]]
*[[Right Hand Rule]]
</div>
</div>

===Week 14===
<div class="toccolours mw-collapsible mw-collapsed">
====Analyzing Motion with and without Torque====
<div class="mw-collapsible-content">
*[[Torque]]
*[[Torque 2]]
*[[Systems with Zero Torque]]
*[[Systems with Nonzero Torque]]
*[[Torque vs Work]]
*[[Gyroscopes]]
</div>
</div>

===Week 15===
<div class="toccolours mw-collapsible mw-collapsed">
====Introduction to Quantum Concepts====
<div class="mw-collapsible-content">
*[[Bohr Model]]
*[[Energy graphs and the Bohr model]]
*[[Quantized energy levels]]
</div>
</div>
</div>

<div style="float:left; width:30%; padding:1%;">
==Physics 2==
===Week 1===
<div class="toccolours mw-collapsible mw-collapsed">
====3D Vectors====
<div class="mw-collapsible-content">
*[[Vectors]]
*[[Right-Hand Rule]]
*[[Right Hand Rule]]
</div>
</div>

<div class="toccolours mw-collapsible mw-collapsed">
====Electric field====
<div class="mw-collapsible-content">
*[[Electric Field]]
</div>
</div>

<div class="toccolours mw-collapsible mw-collapsed">
====Electric force====
<div class="mw-collapsible-content">
*[[Electric Force]]
*[[Lorentz Force]]
</div>
</div>

<div class="toccolours mw-collapsible mw-collapsed">
Aniruddha Nadkarni

====Electric field of a point particle====
<div class="mw-collapsible-content">
*[[Point Charge]]
</div>
</div>

<div class="toccolours mw-collapsible mw-collapsed">

====Superposition====
<div class="mw-collapsible-content">
*[[Superposition Principle]]
*[[Superposition principle]]
</div>
</div>

<div class="toccolours mw-collapsible mw-collapsed">
====Dipoles====
<div class="mw-collapsible-content">
*[[Electric Dipole]]
*[[Magnetic Dipole]]
</div>
</div>

===Week 2===
<div class="toccolours mw-collapsible mw-collapsed">
====Interactions of charged objects====
<div class="mw-collapsible-content">
*[[Electric Field]]
*[[Electric Potential]]
*[[Electric Force]]
*[[Lorentz Force]]
</div>
</div>

<div class="toccolours mw-collapsible mw-collapsed">
====Tape experiments====
<div class="mw-collapsible-content">
*[[Polarization]]
*[[Electric Polarization]]
</div>
</div>

<div class="toccolours mw-collapsible mw-collapsed">
====Polarization====
<div class="mw-collapsible-content">
*[[Polarization]]
*[[Electric Polarization]]
*[[Polarization of an Atom]]
</div>
</div>

===Week 3===
<div class="toccolours mw-collapsible mw-collapsed">
====Insulators====
<div class="mw-collapsible-content">
*[[Insulators]]
*[[Potential Difference in an Insulator]]
*[[Charged Conductor and Charged Insulator]]
*[[Charged conductor and charged insulator]]
</div>
</div>

<div class="toccolours mw-collapsible mw-collapsed">
====Conductors====
<div class="mw-collapsible-content">
*[[Conductivity]]
*[[Charge Transfer]]
*[[Resistivity]]
*[[Polarization of a conductor]]
*[[Charged Conductor and Charged Insulator]]
*[[Charged conductor and charged insulator]]
</div>
</div>

<div class="toccolours mw-collapsible mw-collapsed">
====Charging and discharging====
<div class="mw-collapsible-content">
*[[Charge Transfer]]
*[[Electrostatic Discharge]]
*[[Charged Conductor and Charged Insulator]]
*[[Charged conductor and charged insulator]]
</div>
</div>

===Week 4===
<div class="toccolours mw-collapsible mw-collapsed">
====Field of a charged rod====
<div class="mw-collapsible-content">
*[[Charged Rod]]
</div>
</div>

<div class="toccolours mw-collapsible mw-collapsed">
====Field of a charged ring/disk/capacitor====
<div class="mw-collapsible-content">
*[[Charged Ring]]
*[[Charged Disk]]
*[[Charged Capacitor]]
</div>
</div>

<div class="toccolours mw-collapsible mw-collapsed">
====Field of a charged sphere====
<div class="mw-collapsible-content">
*[[Charged Spherical Shell]]
*[[Field of a Charged Ball]]
</div>
</div>

===Week 5===
<div class="toccolours mw-collapsible mw-collapsed">
====Potential energy====
<div class="mw-collapsible-content">
*[[Potential Energy - Claimed by Janki Patel]]
</div>
</div>

<div class="toccolours mw-collapsible mw-collapsed">
====Electric potential====
<div class="mw-collapsible-content">
*[[Electric Potential]]
*[[Path Independence of Electric Potential]]
*[[Potential Difference Path Independence, claimed by Aditya Mohile]]
*[[Potential Difference in a Uniform Field]]
*[[Potential Difference of Point Charge in a Non-Uniform Field]]
</div>
</div>
<div class="toccolours mw-collapsible mw-collapsed">
====Sign of a potential difference====
<div class="mw-collapsible-content">
*[[Sign of a Potential Difference]]
</div>
</div>
<div class="toccolours mw-collapsible mw-collapsed">
====Potential at a single location====
<div class="mw-collapsible-content">
*[[Electric Potential]]
*[[Potential Difference at One Location]]
</div>
</div>

<div class="toccolours mw-collapsible mw-collapsed">

====Path independence and round trip potential====
<div class="mw-collapsible-content">
*[[Path Independence of Electric Potential]]
*[[Potential Difference Path Independence, claimed by Aditya Mohile]]
</div>
</div>

===Week 6===
<div class="toccolours mw-collapsible mw-collapsed">
====Electric field and potential in an insulator====
<div class="mw-collapsible-content">
*[[Potential Difference in an Insulator]]
*[[Electric Field in an Insulator]]
</div>
</div>
<div class="toccolours mw-collapsible mw-collapsed">
====Moving charges in a magnetic field====
<div class="mw-collapsible-content">
*[[Magnetic Field]]
*[[Magnetic Force]]
*[[Lorentz Force]]
</div>
</div>
<div class="toccolours mw-collapsible mw-collapsed">
====Biot-Savart Law====
<div class="mw-collapsible-content">
*[[Biot-Savart Law]]
*[[Biot-Savart Law for Currents]]
</div>
</div>
<div class="toccolours mw-collapsible mw-collapsed">
====Moving charges, electron current, and conventional current====
<div class="mw-collapsible-content">
*[[Moving Point Charge]]
*[[Current]]
</div>
</div>

===Week 7===
<div class="toccolours mw-collapsible mw-collapsed">
====Magnetic field of a wire====
<div class="mw-collapsible-content">
*[[Magnetic Field of a Long Straight Wire]]
</div>
</div>

<div class="toccolours mw-collapsible mw-collapsed">
====Magnetic field of a current-carrying loop====
<div class="mw-collapsible-content">
*[[Magnetic Field of a Loop]]
</div>
</div>

<div class="toccolours mw-collapsible mw-collapsed">
====Magnetic dipoles====
<div class="mw-collapsible-content">
*[[Magnetic Dipole Moment]]
*[[Bar Magnet]]
</div>
</div>

<div class="toccolours mw-collapsible mw-collapsed">
====Atomic structure of magnets====
<div class="mw-collapsible-content">
*[[Atomic Structure of Magnets]]
</div>
</div>

===Week 8===
<div class="toccolours mw-collapsible mw-collapsed">
====Steady state current====
<div class="mw-collapsible-content">
*[[Steady State]]
*[[Non Steady State]]
</div>
</div>

<div class="toccolours mw-collapsible mw-collapsed">
====Node rule====
<div class="mw-collapsible-content">
*[[Node Rule]]
</div>
</div>

<div class="toccolours mw-collapsible mw-collapsed">
====Electric fields and energy in circuits====
<div class="mw-collapsible-content">
*[[Series circuit]]
*[[Node Rule]]
*[[Loop Rule]]
*[[Electric Potential Difference]]
</div>
</div>

<div class="toccolours mw-collapsible mw-collapsed">
====Macroscopic analysis of circuits====
<div class="mw-collapsible-content">
*[[Series Circuits]]
*[[Parallel CIrcuits]]
*[[Parallel Circuits vs. Series Circuits*]]
*[[Loop Rule]]
*[[Node Rule]]
*[[Fundamentals of Resistance]]
</div>
</div>

===Week 9===
<div class="toccolours mw-collapsible mw-collapsed">
====Electric field and potential in circuits with capacitors====
<div class="mw-collapsible-content">
*[[Charging and Discharging a Capacitor]]
*[[RC Circuit]]
*[[R Circuit]]
*[[AC and DC]]
</div>
</div>

<div class="toccolours mw-collapsible mw-collapsed">
====Magnetic forces on charges and currents====
<div class="mw-collapsible-content">
*[[Magnetic Force]]
*[[Lorentz Force]]
*[[Applying Magnetic Force to Currents]]
*[[Magnetic Force in a Moving Reference Frame]]
*[[Right-Hand Rule]]
*[[Analysis of Railgun vs Coil gun technologies]]
</div>
</div>

<div class="toccolours mw-collapsible mw-collapsed">
====Electric and magnetic forces====
<div class="mw-collapsible-content">
*[[Electric Force]]
*[[Magnetic Force]]
*[[Lorentz Force]]
*[[VPython Modelling of Electric and Magnetic Forces]]
</div>
</div>

<div class="toccolours mw-collapsible mw-collapsed">
====Velocity selector====
<div class="mw-collapsible-content">
*[[Lorentz Force]]
*[[Combining Electric and Magnetic Forces]]
</div>
</div>

===Week 10===
<div class="toccolours mw-collapsible mw-collapsed">
====The Hall effect====
<div class="mw-collapsible-content">
*[[Hall Effect]]
*[[Right-Hand Rule]]
*[[Motional Emf]]
*[[Magnetic Force]]
*[[Magnetic Torque]]
</div>
</div>

<div class="toccolours mw-collapsible mw-collapsed">
====Motional EMF====
<div class="mw-collapsible-content">
*[[Motional Emf]]
*[[Motional Emf using Faraday's Law]]
</div>
</div>

<div class="toccolours mw-collapsible mw-collapsed">
====Magnetic force====
<div class="mw-collapsible-content">
*[[Magnetic Force]]
*[[Lorentz Force]]
</div>
</div>

<div class="toccolours mw-collapsible mw-collapsed">
====Magnetic torque====
<div class="mw-collapsible-content">
*[[Magnetic Torque]]
*[[Right-Hand Rule]]
</div>
</div>

===Week 12===

<div class="toccolours mw-collapsible mw-collapsed">
====Gauss's Law====
<div class="mw-collapsible-content">
*[[Gauss's Flux Theorem]]
*[[Gauss's Law]]
*[[Magnetic Flux]]
</div>
</div>

<div class="toccolours mw-collapsible mw-collapsed">
====Ampere's Law====
<div class="mw-collapsible-content">
*[[Ampere's Law]]
*[[Ampere-Maxwell Law]]
*[[Magnetic Field of Coaxial Cable Using Ampere's Law]]
*[[Magnetic Field of a Long Thick Wire Using Ampere's Law]]
*[[Magnetic Field of a Toroid Using Ampere's Law]]
*[[Magnetic Field of a Solenoid Using Ampere's Law]]
*[[The Differential Form of Ampere's Law]]
</div>
</div>

===Week 13===
<div class="toccolours mw-collapsible mw-collapsed">
====Semiconductors====
<div class="mw-collapsible-content">
*[[Semiconductor Devices]]
</div>
</div>

<div class="toccolours mw-collapsible mw-collapsed">
====Faraday's Law====
<div class="mw-collapsible-content">
*[[Faraday's Law]]
*[[Motional Emf using Faraday's Law]]
*[[Lenz's Law]]
</div>
</div>

<div class="toccolours mw-collapsible mw-collapsed">
====Maxwell's equations====
<div class="mw-collapsible-content">
*[[Gauss's Law]]
*[[Magnetic Flux]]
*[[Ampere's Law]]
*[[Faraday's Law]]
*[[Maxwell's Electromagnetic Theory]]
</div>
</div>

===Week 14===
<div class="toccolours mw-collapsible mw-collapsed">
====Circuits revisited====
<div class="mw-collapsible-content">

*[[RLC Circuits]]
*[[LR Circuits]]
</div>
</div>

<div class="toccolours mw-collapsible mw-collapsed">

====Inductors====
<div class="mw-collapsible-content">
*[[Inductors]]
*[[Current in an LC Circuit]]
</div>
</div>

===Week 15===
<div class="toccolours mw-collapsible mw-collapsed">
==== Electromagnetic Radiation ====
<div class="mw-collapsible-content">
*[[Electromagnetic Radiation]]
</div>
</div>

<div class="toccolours mw-collapsible mw-collapsed">
====Sparks in the air====
<div class="mw-collapsible-content">
*[[Sparks in Air]]
*[[Spark Plugs]]
</div>
</div>

<div class="toccolours mw-collapsible mw-collapsed">
====Superconductors====
<div class="mw-collapsible-content">
*[[Superconducters]]
*[[Superconductors]]
*[[Meissner effect]]
</div>
</div>
</div>

<div style="float:left; width:30%; padding:1%;">

==Physics 3==

===Week 1===
<div class="toccolours mw-collapsible mw-collapsed">
====Classical Physics====
<div class="mw-collapsible-content">
</div>
</div>

===Week 2===
<div class="toccolours mw-collapsible mw-collapsed">
====Special Relativity====
<div class="mw-collapsible-content">
*[[Frame of Reference]]
*[[Einstein's Theory of Special Relativity]]
*[[Time Dilation]]
*[[Einstein's Theory of General Relativity]]
*[[Albert A. Micheleson & Edward W. Morley]]
*[[Magnetic Force in a Moving Reference Frame]]
</div>
</div>

===Week 3===
<div class="toccolours mw-collapsible mw-collapsed">
====Photons====
<div class="mw-collapsible-content">
*[[Spontaneous Photon Emission]]
*[[Light Scattering: Why is the Sky Blue]]
*[[Lasers]]
*[[Electronic Energy Levels and Photons]]
*[[Quantum Properties of Light]]
</div>
</div>

===Week 4===
<div class="toccolours mw-collapsible mw-collapsed">
====Matter Waves====
<div class="mw-collapsible-content">
*[[Wave-Particle Duality]]
</div>
</div>

===Week 5===
<div class="toccolours mw-collapsible mw-collapsed">
====Wave Mechanics====
<div class="mw-collapsible-content">
*[[Standing Waves]]
*[[Wavelength]]
*[[Wavelength and Frequency]]
*[[Mechanical Waves]]
*[[Transverse and Longitudinal Waves]]
</div>
</div>

===Week 6===
<div class="toccolours mw-collapsible mw-collapsed">
====Rutherford-Bohr Model====
<div class="mw-collapsible-content">
*[[Rutherford Experiment and Atomic Collisions]]
*[[Bohr Model]]
*[[Quantized energy levels]]
*[[Energy graphs and the Bohr model]]
</div>
</div>

===Week 7===
<div class="toccolours mw-collapsible mw-collapsed">
====The Hydrogen Atom====
<div class="mw-collapsible-content">
*[[Quantum Theory]]
*[[Atomic Theory]]
</div>
</div>

===Week 8===
<div class="toccolours mw-collapsible mw-collapsed">
====Many-Electron Atoms====
<div class="mw-collapsible-content">
*[[Quantum Theory]]
*[[Atomic Theory]]
*[[Pauli exclusion principle]]
</div>
</div>

===Week 9===
<div class="toccolours mw-collapsible mw-collapsed">
====Molecules====
<div class="mw-collapsible-content">
</div>
</div>

===Week 10===
<div class="toccolours mw-collapsible mw-collapsed">
====Statistical Physics====
<div class="mw-collapsible-content">
</div>
</div>

===Week 11===
<div class="toccolours mw-collapsible mw-collapsed">
====Condensed Matter Physics====
<div class="mw-collapsible-content">
</div>
</div>

===Week 12===
<div class="toccolours mw-collapsible mw-collapsed">
====The Nucleus====
<div class="mw-collapsible-content">
</div>
</div>

===Week 13===
<div class="toccolours mw-collapsible mw-collapsed">
====Nuclear Physics====
<div class="mw-collapsible-content">
*[[Nuclear Fission]]
*[[Nuclear Energy from Fission and Fusion]]
</div>
</div>

===Week 14===
<div class="toccolours mw-collapsible mw-collapsed">
====Particle Physics====
<div class="mw-collapsible-content">
*[[Elementary Particles and Particle Physics Theory]]
*[[String Theory]]
</div>
</div>
</div>

Charge Transfer

2016-11-25T02:50:54Z

Sboyce7:

claimed by Lzhang375

claimed for editing and additional examples- Samuel Boyce Fall 2016

If a charged conductor comes in contact, or is in close enough proximity, with another conductor, it is possible to transfer this charge to the second conductor. This process is called '''charge transfer'''. Charges cannot be created or destroyed; this is known as the ''Law of Conservation of Charge''. Therefore, in the transfer of charge between two objects, the amount of charge gained by one object is equal to the amount of charge loss by the other. There are multiple ways that charge can be transferred such as through direct contact and through inductance.

==Insulators vs Conductors==

In an '''insulator''', electrons are bounded tightly to atoms, which prevents charged particles from moving through the material. If charge is transferred to an insulator at a given location, the charge will remain at the location that the transfer occurred.

[[File:inschargedist.gif|thumb|180px|Charges transferred to an insulator remains at the location of transfer.]]

On the other hand, electrons are able to flow freely from particle to particle within '''conductors'''. When charge is transferred to a conductor, the charge is distributed evenly across the surface of the object via ''electron movement''. The electrons will be distributed until the repelling force between the excess electrons is minimized. This is the main difference between insulators and conductors: insulators do not have mobile charged particles whereas conductors have mobile charged particles that allow for charge transfer through the free movement of electrons. Examples of insulators include rubber and air and examples of conductors include metals and salt water.

==Transfer Charges by Conduction==

Electrons move from one object to another (especially with metals) through points of contact. An example of this is rubbing a glass rod with silk. The glass rod will become positively charged and the silk will become negatively charged; this means that electrons were transferred from the glass rod to the silk, since protons are not removed from the nuclei. Rubbing two objects together is not necessary for charge transfer, but because rubbing creates more points of contact between two objects, it facilitates charge transfer.

[[File:Conductiontransfer.gif]]

==Transfer Charges by Induction==

Unlike the transfer of charges by conduction, objects that becomes charged to each other do not require points of contact. When an object is charged, it has an electric field. This electric field will repel or attract electrons in another object. This electron movement is called transfer of charges by induction. A neutral object can be charged by another charged object through a process called '''polarization'''. This is when electrons in the object is repelled or attracted to one side of the object by the charged second object. For example, if a negatively charged sphere is placed near a neutral sphere, the electrons in the neutral sphere will be repelled by the charged sphere. The neutral sphere is now polarized, with one side of it being negatively charged and the other side being positively charged. The negatively charged side of the sphere can be removed through grounding or with a conductor. Once removed, the originally neutral sphere will now be positively charged. Another example of induction is the balloon and black pepper experiment. A balloon can be given a negative charge by rubbing it on hair. When the balloon is placed near grounded black pepper, the black pepper particles will be polarized so that it becomes positively charged on top and will be attracted to the negatively charged balloon.

[[File:Indtransfer.gif]]

== See also ==

http://www.physicsbook.gatech.edu/Charge_Motion_in_Metals

http://www.physicsbook.gatech.edu/Polarization

==References==

Internet resources on this topic:

http://www.physicsclassroom.com/class/estatics/Lesson-1/Conductors-and-Insulators

http://www.physicsclassroom.com/class/estatics/Lesson-1/Charge-Interactions

Chabay, Ruth W., Bruce Sherwood. Matter and Interactions, Volume II: Electric and Magnetic Interactions, 4th Edition. Wiley, 19/2015. VitalBook file.

[[Category:Which Category did you place this in?]]