Electricity

Question 1

What is electric charge?

Answer 1

It is a fundamental property of matter that cannot be defined but existence and effect can be shown

Question 2

What is a Coulomb?

Answer 2

1 Amp per second

Question 3

Coulomb’s Law

Answer 3

t

Question 4

Surface-density of a charge…

Answer 4

Increases with curvature

Question 5

Electric field

Answer 5

=F/Q

=kQ/r^2

Question 6

Electric field in a charged sphere=

Answer 6

0

Question 7

Electric Potential

Answer 7

It is when a charge Q’ is moved between two points in an electric field

W= Change in EPE

V=kQ/r

Question 8

Potential Difference (V)

Answer 8

The energy transferred in moving a positive charge from a lower potential to a higher one

V=W/Q

Causes charge to move

Current flows from high to low potential

Question 9

Current

Answer 9

The rate of charge transfer

Amps

Question 10

I=

Answer 10

Anev

Area of wire*Number of electrons*Charge of electrons*Average Drift Velocity

Question 11

Current density, J=

Answer 11

I/A=nev

Question 12

Define Resistance

Answer 12

Anything that impedes the flow of charge such as componenets or wires

R=V/I

In Ohms

Question 13

Ohm’s Law

Answer 13

Constant temperature = Constant Resistance

Question 14

Define Resisitivity

Answer 14

How strongly a material resists current flow

Question 15

Direct Current DC

Answer 15

Majority of devices use this

Steady current flows in one diirection

Question 16

EMF

Answer 16

Amount oof energy converted into electrical potential energy per unit charge

Question 17

Voltage drop

Answer 17

Amount of electrical potential energy converted into other energy per unit charge

Question 18

Krichoff’s First Law

Answer 18

The sum of the currents into a junction=The sum of the currents out of the junction

Question 19

Kirchoff’s Second Law

Answer 19

In any circuit loop, the sum of the emfs=the sum of the pds

Question 20

To find Internal resistance

Answer 20

EMF=I(R+r)