Question

A particle with a charge of 2e moves between two points which have a potential difference of 75V. What is the change in potential energy of the particle?

Answer 1

Electric potential energy is defined as Ep=Q*V where Q is the magnitude of the charge and V is the potential difference. So when a charge moves between the points that have a potential difference, it's energy changes. 

In our case: 

Q=2e=2*(-1.6*10^-19) C
V=75 V

Ep=(-3.2*10^-19)*75

Ep=-2.4*10^-17 J

The change in potential energy of the charge is -2.4*10^-17 J