In a spherical distribution, the charge density varies as $\mathrm{\rho }\left(\mathrm{r}\right)=\raisebox{1ex}{$\mathrm{A}$}\!\left/ \!\raisebox{-1ex}{$\mathrm{r}$}\right.$ for $\mathrm{a}<\mathrm{r}<\mathrm{b}$ (as shown) where $\mathrm{A}$ is a constant. A point charge $\mathrm{Q}$ lies at the centre of the sphere at $\mathrm{r}=0$. The electric field in the region $\mathrm{a}<\mathrm{r}<\mathrm{b}$ has a constant magnitude for