physic 難題 41

SInce the given electric field is a uniform field from left to right, the equipotentials are vertical parallel lines with decreasing potential from left to right.

Potential difference between X and Y
V = E.[l.sin(60)] where [l.sin(60)] is the separation between the two equipotentials that passing through points X and Y.

Work done in moving a 1 C charge from X to Y
= charge x potential difference between X and Y
= 1 x [-E.l.sin(60)] the -ve sign indicates that potential at Y is lower than that at X
= -E.l.sin(60)

Since YZ lies on an equipotential, there is no work done in moving the charge. Hence, work done in moving the charge from Y to Z = 0

The answer is thus option D.