The electrostatic potential in a charged spherical region of radius r varies as V=a r^3+b, where a and b are constants. The total charge in the…

The electrostatic potential in a charged spherical region of radius $\displaystyle r$ varies as $\displaystyle V=a r^3+b$, where $\displaystyle a$ and $\displaystyle b$ are constants. The total charge in the sphere of unit radius is $\displaystyle \alpha \times \pi a \in_{\mathrm{o}}$. The value of $\displaystyle \alpha$ is $\displaystyle \_\_\_\_$. (permittivity of vacuum is $\displaystyle \epsilon_0$ )