Chapter-1|Electric Charges and Fields | NCERT 12th Physics:
(III) Field Due to a Uniformly Charged Thin Spherical Shell:
Let σ be the uniform surface charge density of a thin spherical shell of radius R. The Gaussion surface will be a spherical surface centred at the centre of shell.
(a) At a point outside the Shell: (r>R)
Since E and n^ are in the same direction, So θ=0
Flux through the Gaussian surface-
(b) At the point on the surface of the Shell:(r=R)
(c) At the point inside the Shell:
Since the charges inside the gaussian surface is zero.
Since the charges inside the gaussian surface is zero.
Hence, Electric field due to a uniformly charged spherical shell is zero at all points inside the shell.