Question

Two identical simple pendulums, $A$ and $B$, are suspended from the same point. The bobs are given positive charges, with $A$ having more charge than $B$. They diverge and reach equilibrium, with $A$ and $B$ making angles $\theta_{1}$ and $\theta_{2}$ with the vertical respectively. Which of the following is correct?

• A. $\theta_{1}>\theta_{2}$
• B. $\theta_{1}<\theta_{2}$
• C. $\theta_{1}=\theta_{2}$
• D. The tension in $A$ is greater than that in $B$.

Answer 1

Answer: (C)

The pendulums are identical. Each pendulum is in equilibrium, under the action of three forces namely: weight, electric repulsion and tension. As weight and electric repulsion are same, tension too must be same.
Hence $\theta_{1}=\theta_{2}$