The electric potential at a distance d from a point charge is V. At a distance d', the potential is 2V. What is the ratio of electric field at d' to that at d?

Question

Quizplus · Accepted Answer

The electric potential V due to a point charge is inversely proportional to the distance (V ∝ 1/r). If the potential at d' is 2V, then d' = d/2. The electric field E is inversely proportional to the square of the distance (E ∝ 1/r^2). Therefore, the ratio of electric fields E(d')/E(d) = (d/d')^2 = (d/(d/2))^2 = 4.

The Electric Potential at a Distance D from a Point