Question

A proton released from rest in a region of a uniform electric field undergoes a displacement through a potential difference of -300 V. The change in its kinetic energy (in eV) is

Answer 1

Explanation:

Since the field is uniform, the potential difference will be given by the product of the electric field and the distance. so it will be 8×0.5×10

4

=4×10

4

VChange in potential energy will be the work done by the proton.

That will be charge×PD

We know that one proton charge is 1.6×10

−19

C

Hence the answer is −6.4×10

−15

J

The negative sign shows that the PE decreases as the proton does work.