Question

A uniform electric field E exists between two charged plates . What would be the work done in moving a charge q along the closed rectangular path ABCDA (rectangle is between the plates)

Answer 1

no work is done as it is a closed path and field is perpendicular to motion.
E.ds cos90=0

Answer 2

The work done would be zero when the charge q moves along the closed rectangular path ABCDA between plates.  

Given:

The uniform electric field E existing between two plates has a charge movement of q with a rectangular path ABCDA between the plates.  

Solution:

So the amount of work done is to be calculated which is totally based on the force of the field that is electrostatic force and the distance travelled.  

Work done is also dependent upon the path followed. Here the path followed is rectangular and is seen to be perpendicular to the field.  

Thus $\begin{aligned} W &=E \cdot d s \cos \theta \\ W &=E \cdot d s \cos 90 \\ W &=E. d s \times 0 \\ W &=0 \end{aligned}$