Answer
$0.125$
Work Step by Step
The volume of a sphere is given as $V=\frac{4}{3}\pi r^3$.
Given that the radius of the sphere is $R$ for $r=\frac{R}{2}$ , we have volume $V=\frac{4}{3}\pi (\frac{R}{2})^3=\frac{4}{3}\pi(\frac{R^3}{8}) $
This shows that volume is reduced to $\frac{1}{8}$ of the original volume. Thus , the fraction of the charge contained is: $\frac{1}{8}=0.125$.
