A spherical shell of radius 20 cm has ` 20 mu C ` charge placed in vacuum. Calculate the electric field intensity (i) at a distance of 15 cm and (ii) at a distance of 40 cm from the centre of the spherical shell.

Explanation

(i) Electric field intensity at a distance of 15 cm from the centre of the spherical shell = 0 , because charge does not reside inside a charged spherical shell.
(ii) Electric field intensity at a distance of 40 cm or 0.4 m from the centre of the spherical shell,
` E = (1 )/( 4 pi in _ 0) * ( q ) /( x ^ 2 ) = ( 9 xx 10 ^( 9) xx 20 xx 10 ^( -6))/((0.4)^ 2 ) `
` = 1.125 xx 10 ^( 6 ) N * C ^( -1 ) `