A conducting sphere of radius 10 cm has an unknown charge. If the electric field 20cm from the centre of the sphere is `1.5 xx 10^(3) N.C^(-1)` and points radially inward, what is the net charge on the sphere ?

Explanation

Electric field,
`E = (1)/( 4) pi in_(0) (q)/( r^(2))`
`:. q= ( Er^(2))/(((1)/( 4piin_(0))))= ( 1.5 xx 10^(3) xx ( 0.2 )^(2))/( 9 xx 10^(9)) C = 6.67 nC `