In question number 45, what will be the electric field at O if the charge q at A is replaced by -q?

Options

A. `(q)/(4piepsilon_(0)r^(2))` along OB
B. `(2q)/(4piepsilon_(0)r^(2))` along OA
C. `(4q)/(4piepsilon_(0)r^(2))` along OC
D. zero

Answer

B

Explanation

If the charge q at A is replaced by -q, it is equivalent to adding charge -2q at A. Therefore, electric field at O, `E_(2)=(2q)/(4piepsilon_(0)r^(2)` along OA.