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 ).

Explanation

We know for a spherical surface flux
`E xx ds = (Q/ epsilon_0)`
(By Gauss, s law)
Hence for a hemisphere, Total flux at
surface
` = Q/epsilon_0 xx 1/2 = (Q/2 epsilon_0)` .