Two charges lie on the x axis, +3q at the origin, and −2q at x = 5.0 m. The point on the x axis where the electric potential has a zero value (when the value at infinity is also zero) is
A) 1.0 m.
B) 2.0 m.
C) 2.5 m.
D) 3.0 m.
E) 4.0 m.

Question

Quizplus · Accepted Answer

The electric potential is zero where the potentials due to both charges cancel each other out. The potential due to a point charge is V = kq/r. Setting the potentials equal and opposite, solve for the distance from the origin: (3q/x) = (2q/(5-x)). Solving gives x = 3.0 m.

Two Charges Lie on the X Axis, +3q at the Origin