Figures (a) and (b) show the field lines of a positive and negative point charge respectively.

(a) Give the signs of the potential difference `V_(P)-V_(Q), V_(B)-V_(A)`.
(b) Give the sign of the potential energy difference of a small negative charge between the points Q and P, A and B.
(c) Give the sign of the work done by the field in moving a small positive charge from Q to P.
(d) Give the sign of the work done by the external agency in moving a small negative charge from B to A.
(e) Does the kinetic energy of a small negative charge increase or decrease in going from B to A?

Explanation

A small negative charge will be attracted towards positive charge. The negative charge moves from higher potential energy to lower potential energy . Therefore the sign of potential energy difference from Q to P is negative.
Similarly `(PE)_(A) gt ( PE)_(B)` and hence sign of potential energy difference is negative.
( c) In moving a small positive charge from Q to P work to be done by an external agency against the electric field . Therefore work done by the field is negative .
(d) In moving a small negative charge from B to A work has to be done by the external agency It is positive.
( e) Due to force of repulsion on the negative charge velocity decreases and hence the kinetic energy decreases in going from B to A.