A charge q is placed at the centre of the line joining two equal charges Q. The system of the three charges will be in equilibrium if q is equal to:

Options

A. `-(Q)/(2)`
B. `-(Q)/(4)`
C. `+(Q)/(4)`
D. `+(Q)/(2)`

Answer

b

Explanation

Soppose in the following figure, equilibrium of charge `B` is considered. Hence for its equilibrium
`|F_(A)|=|F_(C)|`
`implies (1)/(4piepsilon_(0))(Q_(2))/(4x^(2))= (1)/(4piepsilon_(0))(qQ)/(x^(2))impliesq= (-Q)/(4)`