A positive point charge q is carried from a point B to a point A in the electric field of a point charge +Q at O. If the permittivity of free space is `epsi_0`, the work done in the process is given by (where `a = OA` and `b = OB`) -

Options

A. `(qQ)/(4pi epsilon_(0))(1/a+1/b)`
B. `(qQ)/(4piepsilon_(0))(1/a-1/b)`
C. `(qQ)/(4piepsilon_(0))(1/(a^(2))-1/(b^(2)))`
D. `(qQ)/(4 pi epsilon_(0))(1/(a^(2))+1/(b^(2)))`

Answer

B

Explanation

`W_(BA)=q(V_(A)-V_(B))`
`=q[Q/(4pi epsilon_(0)a)-Q/(4pi epsilon_(0)b)]=(qQ)/(4 pi epsilon_(0))[1/a-1/b]`