Question

A charge of `4 C` is passing through points A and B on a circuit. If the charge's electric potential changes from `27 J` to `3 J`, what is the voltage between points A and B?

Answer 1

If a charge `Q` passes through the points `A` and `B`; and the difference of the electric potential between points `A` and `B` is `DeltaW`. Then the voltage `DeltaV` between the two points is given by:

`DeltaV=(DeltaW)/Q`

Let the electric potential at point `A` be denoted by `W_A` and let the electric potential at point `B` be denoted by `W_B`.

`implies W_A=27J` and `W_B=3J`

Since the charge is moving from `A` to `B` therefore the difference of electrical potential between points can be found out by:
`W_B-W_A`
`=3J-27J=-24J`

`implies DeltaW=-24J`

It is given that charge `Q=4C`.

`implies DeltaV=(-24J)/4=-6`Volt

`implies DeltaV=-6`Volt

Hence, the voltage between points `A` and `B` is `-6`Volt.

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