Question

A point charge q produces an electric field of magnitude $2N{C}^{-1}$ at a point distant 0.25 m from it. Find the value of charge.

Answer 1

Intensity of the electric field at a point is,
$E=\frac{1}{4\pi {ϵ}_0}\frac{q}{d^2}$
$\Rightarrow q=4\pi {ϵ}_0\times d^2\times E=\frac{1}{9\times {10}^9}\times (0.25{)}^2\times 2=1.39\times {10}^{-11}C$