A pendulum of length $L$ carries a negative charge $-q$ on the bob. A positive charge $+q$ is held at the point of support. Then, the time period of the bob is

• A

  Greater than$2\pi \sqrt{\frac{L}{\mathrm{g}}}$
• B

  Less than $2\pi \sqrt{\frac{L}{\mathrm{g}}}$
• Correct answer
  C

  equal to $2\pi \sqrt{\frac{L}{\mathrm{g}}}$
• D

  Equal to $2\pi \sqrt{\frac{2L}{\mathrm{g}}}$

Solution

There is no change in the restoring force as the electrostatic forces are the central forces. Negative and positive charges at the two extremities of the string affect tension $T$ which does not affect the restoring force

       

Hence, the correct answer is option: 'C'.