# Electric fields Flashcards Preview

## Physics - Electricity and magnetism > Electric fields > Flashcards

Flashcards in Electric fields Deck (9)
1
Q

Value of e (electric charge on a proton)

A

1.6 * 10-19 C

Charge on electron is -e

2
Q

Law of conservation of charge

A

Charge cannot be created or destroyed. Total charge does not change

3
Q

What did the Tolman-Stewart experiment prove?

A

Electrons are the charge carriers in metals

4
Q

Describe Tolman-Stewart experiment

A
• If negative electrons are charge carriers, they should be free to move while positive charges stay fixed
• If metal is suddenly accelerated with a very large a, electrons would be thrown back
• Creates excess negative charge at back and excess positive charge at front
• Excess charge was measured-found to be consistent with negative charge carriers in metals
5
Q

Coulomb’s law in words

A

Electric force between two charges q1 and q2 is:
1. Propotional to product of two charges
2. Inversely proportional to square of seperation of charges

6
Q

Coulomb’s law (formula)

A

F= k (q1 q2 /r2)

k = 8.99 * 109 Nm2 C-2 in vaccum/ air

7
Q

Constant k also written as?

A

1/4πεo

8
Q

How to test a space for an electric field

A

If test charge q(positve) experiences an electric force, there is a field. q must be small so it doesn’t disturb the electric field it is trying to detect.

9
Q

Electric field strength formula

A

E=F/q
electric force per unit charge
∴ E=k(Q/r2

Also applies outside a conducting sphere with charge q on surface