Two-point charges $+Q$ and $+q$ repel each other with a force of $100 \mathrm{~N}$. Keeping the distance…
Two-point charges $+Q$ and $+q$ repel each other with a force of $100 \mathrm{~N}$. Keeping the distance between them unchanged, if $Q$ is increased by $10 \%$ and $q$ is decreased by $q$ the force of repulsion between them will.
decrease by $10 \mathrm{~N}$
decrease by $1 \mathrm{~N}$
increase by $10 \mathrm{~N}$
remain same
Solution
Given, $100 \mathrm{~N}=\frac{k Q q}{r^2}$ and $F=\frac{k(1.1 Q)(0.9 q)}{r^2}$
Taking the ratio of above two equations:
$F=99$