Question

The force between two charges separated by a distance 1 m is 1.8 N. The charges are in the ratio 1 : 2 .Then the charges are

• A. $5\mu C,5\mu C$
• B. $5\mu C,10\mu C$
• C. $1\mu C,10\mu C$
• D. $10\mu C,20\mu C$

Answer 1

The correct option is D $10\mu C,20\mu C$

$F=\frac{1}{4\pi {ϵ}_0}\frac{q_1{q}_2}{d^2}\frac{q_1}{q_2}=\frac{1}{2};q_2=2q_1$
$1.8=9\times {10}^9\times \frac{2q_1^2}{(1{)}^2}$
$q_1^2={10}^{-10}$
$q_1={10}^{-5}=10\times {10}^{-6}=10\mu C$
$q_2=20\mu C$