Question

A charge of $1\mu C$ is divided into two parts such that their charges are in the ratio of $2:3$. These two charges are kept at a distance $1m$ apart in vacuum. Then, the electric force between them (in N) is:

• A. $0.216$
• B. $0.00216$
• C. $0.0216$
• D. $2.16$

Answer 1

The correct option is B $0.00216$

Ratio of charges $=2:3$
$\therefore q_1=\frac{2}{5}\times 1\mu C$ and $q_2=\frac{3}{5}\times 1\mu C$

Electrostatic force between the two charges:
$F=\frac{1}{4\pi {\epsilon }_0}\frac{q_1{q}_2}{r^2}$
$=\frac{9\times {10}^9\times 2\times {10}^{-6}\times 3\times {10}^{-6}}{5\times 5\times 1^2}$
$=2.16\times {10}^{-3}N$