question_answer

A solid sphere of radius R has a charge Q distributed in its volume with a charge density \[\rho =k\,{{r}^{a}},\] where k and a are constants and r is the distance from its centre. If the electric field at \[r=\frac{R}{2}\] is \[\frac{1}{8}\] times that at \[r=R,\] find the value of a.

Answer:

(2)