A point charge q moves from point P to pont S along the path PQRS (fig.) in a uniform electric field E pointing parallel to the poistive direction of the X-axis. The coordinates of the points P, Q, R and S are(a, b, O), (2a, O, O)(a, -b,`ulO`) and `(O, O, O) respectively. The work done by the field in the above process is given by the expresison............

Options

A. `qEsqrt(a^(2)+b^(2))`
B. qEb
C. `-qEa`
D. qEa

Answer

C

Explanation

Work done by electric field
`=qvec(E).Deltavec(r)=q(Ehati).[(0hati+0hatj+0hatk)-(ahati+bhatj)]`
=-qEa