Question

A charge of `5 C` is passing through points A and B on a circuit. If the charge's electric potential changes from `27 J` to `7 J`, what is the voltage between points A and B?

Answer 1

`4V`

Explanation:

We use the definition of electrical potential, or Voltage as given by

`V=(Delta E)/Q`

where `V` is the voltage change between two locations, `Delta E` is the change in potential energy and `Q` is the charge that is moving. The change in potential energy in going from A to B (final state being at point B):

`Delta E=7J-27J=-20J`

Then the voltage at B with respect to A is

`V_B=(-20J)/(5C)=-4V`

Therefore, the voltage at point B is `4V` lower than the voltage at point A.