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

Answer

B

Explanation

For equilibrium, net force on q = 0
`therefore" "(kqQ)/((2x)^(2))+(kqQ)/(x^(2))=0`
`therefore" "q=-Q//4`