Question

Two electric charges $12\mu C$ and $- 6\mu C$ are placed 20 cm apart in air. There will be a point P on the line joining these charges and outside the region between them, at which the electric potential is zero. The distance of P from $- 6\mu C$ charge is

• A. 0.10 m
• B. 0.15 m
• C. 0.20 m
• D. 0.25 m

Answer 1

Answer: (C)

0.20 m

Answer 2

Point P will lie near the charge which is smaller in magnitude i.e. – 6 μ C. Hence potential at P

$V = \frac{1}{4\pi\varepsilon_{0}}\frac{( - 6 \times 10^{- 6})}{x} + \frac{1}{4\pi\varepsilon_{0}}\frac{(12 \times 10^{- 6})}{(0.2 + x)} = 0$ ⇒ x = 0.2 m