As per this diagram a point charge `+q` is placed at the origin `O`. Work done in taking another point charge `-Q` from the point `A(0, a)` to another point `B(a, 0)` along the staight path `AB` is:

Options

A. `((-qQ)/(4pi epsilon_(0))(1)/(a^(2)))sqrt(2a)`
B. zero
C. `((qQ)/(4pi epsilon_(0))(1)/(a^(2)))(1)/sqrt(2)`
D. `((qQ)/(4pi epsilon_(0))(1)/(a^(2)))(1)/sqrt(2a)`

Answer

B

Explanation

Change moves `_|_^(r )` to the filed lines. So the work done will be zero.