Two identical pendulums A and B are suspended from the same point. Both are given positive charge, with A having more charge than B. They diverge and reach equilibrium with the suspension of A and B making angles ${\theta }_1$ and ${\theta }_2$ with the vertical respectively.

Given data: Two Pendulums A and B and both have positive charge, $Qa>Qb$, and theta 1 and theta 2 be the angle with vertical that the string of pendulums makes in eq

Concept Used: 

As we know the force of electrostatic acting on 2 charge particle is equal if they kept isolated.

That means it doesn’t matter which bob has more charge, The force acting between them is same and also it is the reason that they will make some angle with vertical.

This is the simple formula of electrostatic force of attraction between two charges. 

$\mathrm{F}=\frac{\mathrm{kQq}}{{\mathrm{r}}^2}$

$\text{ Hence, }{\mathrm{T}}_1={\mathrm{T}}_2\text{, which implies }{\theta }_1={\theta }_2$