A spherical conductor of radius 12 cm has a charge of 1.6 × 10^⁻7 C distributed uniformly on its surface. What is the electric field (a) inside the sphere (b) just outside the sphere (c) at a point 18 cm from the centre of the sphere?

Ans (a).
Radius of the spherical conductor, r = 12 cm = 0.12 m

Charge is uniformly distributed over the conductor, q = 6 x 10^-7 C

Electric field inside a spherical conductor is zero. This is because if there is field inside the conductor, then charges will move to neutralize it.

Ans (b).

Electric field E just outside the conductor is given by the relation,

^E=1/4πε₀ x q/r²

Where, ε₀ = Permittivity of free space and = 9 x 10⁹ Nm²C⁻²

Therefore, E = (9x 10⁹ x 1.6 x 10^-7)/(o.12)²

=10⁵ NC⁻¹

Therefore, the electric field just outside the sphere is 10⁵ NC^-1.

Ans (c).
Electric field at a point 18 m from the centre of the sphere = Ei

Distance of the point from the centre, d = 18 cm = 0.18 m

1 q 9 x 10⁹ x 1.6 x 10^-7

^E=1/4πε₀ x q/d²

= (9x 10⁹ x 1.6 x 10^-7)/(1.8 x 10⁻² )²

= 4.4 x 10⁴ NC^-1

Therefore ,the electric field at a point 18cm from the centre of the sphere is 4.4 x 10⁴ NC^-1