Question

Two charges 5 × 10⁻⁸ C and −3 × 10⁻⁸ C are located 16 cm apart. At what point(s) on the line joining the two charges is the electric potential zero? Take the potential at infinity to be zero.

Answer 1

There are two charges, q₁₌ 5×10^-8 C q₂₌-3×10^-8 C
Distance between the two charges, d = 16 cm = 0.16 m
Consider a point P on the line joining the two charges, as shown in the given figure.

⇒0.8=8r ⇒=0.1m =10cm
Therefore, the potential is zero at a distance of 10 cm from the positive charge between the charges. 

Suppose point P is outside the system of two charges at a distance s from the negative charge, where potential is zero, as shown in the following figure.

Therefore, the potential is zero at a distance of 40 cm from the positive charge outside the system of charges.