Question

Help me please to answer on these questions. Thank you!

1. Is work required to move an electric charge along a line of equipotential? Explain. (Think about the strength of the force along these lines and which way it is pointing.)

2. Points P and Q are on the same equipotential lines in an electric field and points R and S are on a higher equipotential line. Compare the work done by the electric field when an electric particle with a positive charge moves from:

          (a) P to R     (b) S to Q    (c) P to S    (d) R to S

For example, in which case will the greatest amount of work be done? In which case will the work be the least? Defend your answer.

Answer 1

1.

Equipotential line means all points on the line have same potential.

If we follow the equation of work, W = q dV ... dV represents difference in potential, which in this case is zero. Hence work also zero.

2.

Vp = Vq < Vr = Vs

Work done in moving the charge from P to R and in moving from P to S will be same ( as Vs = Vr) and will be highest because Vr-Vp will give max p.d in this case.

Similarly, work in S to Q will give least value. It will be equal to above work but -ve as charge is being moved from high to low, dV will be -ve.

*Work from R to S will be zero