Question

Two unlike charges separated by a distance of $1m$ attract each other with a force of $0.108N$. If the charges are in the ratio $1:3$, the weak charge is :

• A. $2\mu C$
• B. $4\mu C$
• C. $6\mu C$
• D. $5\mu C$

Answer 1

Answer: (A)

$2\mu C$

Let the charges be $q$ and $3q$
given force $=0.108N$
$\Rightarrow 0.108=\frac{K\left(q\right)\left(3q\right)}{(1{)}^2}$
$\Rightarrow 0.108=9\times {10}^9\times 3q^2$

$\Rightarrow q^2=\frac{108\times {10}^{-3}}{9\times 3\times {10}^9}$

$\Rightarrow q^2=4\times {10}^{-12}$
$\Rightarrow q=2\times {10}^{-6}$
$\therefore q=2\mu C$