Question

A charge Q is placed at the centre of an imaginary hemispherical surface. Using symmetry arguments and the Gauss's law, find the flux of the electric field due to this charge through the surface of the hemisphere (figure 30-E3).

Answer 1

We know for a spherical surface flux

$E\times ds=\frac{Q}{{\in }_0}$

(By Gauss,s law)

Hence for a hemisphere, Total flux at surface

$=\frac{Q}{{\in }_0}\times \frac{1}{2}=\frac{Q}{2{\in }_0}$