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) As `V prop (1)/ (r ) , V_(P ) gt V_(Q) ` . Thus `(V_(P) - V_(Q))` is positive. Also `V_(B)` is less negative than `V_(A)`. Thus s `V_(B) gt V_(A)` or `(V_(B)-V_(A))` is positive.
(b) 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 , `(P E)_(2) gt (PE )_(B)` and hence sign of potential energy differences is negative.
(d) In moving a small negative 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 chage,Velocity decreases and hence the kinetice energy decreases in going from B to A.