Three similar charges `+q` are placed on `3` corners of an equilateral triangle `ABC` of side `a`. How many minimum charges should be placed on a circle of radius `a` with centre at `A` so that resultant force on the charge placed at the centre is `(q^(2))/(4pi epsilon_(0)a^(2))` along `x`-axis?

Options

A. 4
B. 6
C. 3
D. Any number

Answer

C

Explanation

Two similar charges should be placed at `D` and `E` so that resultant force at `A` is zero. A similar charge should not be placed at `F`, so that resultant force at a`A` will be `(q^(2))/(4pi epsilon_(0)a^(2))` towards `x`-axis