PHYSICS · Multi-part · A Level · Physics · Fields and their consequences · Fields and their consequences
Problem
Two identical pith balls carry charges of +q and +4q, respectively, and are suspended so that their centres are 10cm apart in air.
(a) Determine the magnitude of the force exerted on each pith ball.
(b) The separation between the pith balls is slowly increased until the force becomes one-fifth of the value found in part (a). Calculate the new separation.
(c) Without altering the separation obtained in part (b), the charge +4q is replaced by −4q. Compute the new force on each pith ball and state its nature (attractive/repulsive).