The electric potential at a distance of 4 m from a certain point charge is 200 V relative to infinity. What is the potential (relative to infinity) at a distance of 2 m from the same charge?
A) 200 V
B) 100 V
C) 600 V
D) 50 V
E) 400 V

Question

Quizplus · Accepted Answer

The electric potential $V$ due to a point charge at a distance $r$ is given by $V = k \frac{Q}{r}$, where $k$ is Coulomb's constant and $Q$ is the charge. If the potential at 4 m is 200 V, then at 2 m (half the distance), the potential would be doubled (since $V$ is inversely proportional to $r$), making it 400 V.

The Electric Potential at a Distance of 4 M from a Certain