Question

Point charge q moves from point P to point S along the path PQRS (figure shown) in a uniform electric field E pointing coparallel to the positive direction of the axis. The coordinates of the points and are and respectively. The work done by the field in the above process is given by the expression

• A. q E a
• B. - q E a
• C. $qEa\sqrt{2}$
• D. $qE\sqrt{\left[\right(2a{)}^2+b^2]}$

Answer 1

The correct option is B - q E a

As electric field is a conservative field
Hence the work done does not depend on path

$\therefore W_{ABCD}=W_{AOD}=W_{AO}+W_{OD}$
$=Fbcos{90}^{\circ }+Facos{180}^{\circ }=0+qEa(-1)=-qEa$