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` and points radially inward, what is the net charge on the sphere?

Explanation

`R=10 cm =10 xx 10^(-2) m, r=20 cm=20 xx 10^(-2)m, E=1.5 xx 10^(3) NC^(-1)`
`F_(1)=9 xx 10^(9) q/r^(2), q=(Er^(2))/(9 xx 10^(9)) =(1.5 xx 10^(3) xx (20 xx 10^(-2))^(2))/(9 xx 10^(9)) =6.67nC`
Charge q=-6.67 nC (since electric field is directed inward)