Q. A spherical conductor of radius 10 cm has a charge of 3.2 × 10^-7 C distributed uniformly. What is the magnitude of electric field at a point 15 cm from the centre of the sphere?

$\mathbf{ }\left(\frac{1}{4{\mathrm{\pi \epsilon }}_0} = 9 \times {10}^9 {\mathrm{Nm}}^2 / C^2\right)$

(1) 1.28 × 10⁷ N/C 

(2) 1.28 × 10⁴ N/C 

(3) 1.28 × 10⁶ N/C 

(4) 1.28 × 10⁵ N/C