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 ${\theta }_1={\theta }_2$