The distance between charges `5.0xx10^(-11)C` and `-2.7xx10^(-11)C` is `0.2 m`. The distance at which a third charge should be placed in order that it will not experience any force along the line joining the two charges is

Options

A. `0.44 m`
B. `0.65 m`
C. `0.556 m`
D. `0.350 m`

Answer

C

Explanation

If two opposite charges are separated by a certain distance, then for its equilibrium a third charge should be kept outside and near the charge which is smaller in magnitude.
Here, suppose third charge `q` is placed at a distance `x` from `-2.7xx10^(-11)C` then for its equilibrium `|F_(1)|=|F_(2)|`

`implies (kQ_(1)q)/((x+0.2)^(2))=(kQ_(2)q)/(x^(2))implies x= 0.556m`
(Here `K= 1/(4piepsilon_(0))` and `Q_(1)= 5xx10^(-11)C,Q_(2)= -2.7xx10^(-11)C`)