Question

A pendulum bob carries a +ve charge +q. A positive charge +q is held at the point of support. Then the time period of the bob is (where L = length of pendulum, gₑₓtₑff = effective value of g):

• A. greater than 2π√Lgₑₓtₑff
• B. less than 2π√Lgₑₓtₑff
• C. equal to 2π√Lgₑₓtₑff
• D. equal to 2π√2Lgₑₓtₑff

Hint:

Any force opposing gravity increases the time period of a pendulum.

Answer 1

The Correct Option is A

Step 1: The positive charge at the support repels the positively charged bob.
Step 2: This electrostatic repulsion acts upward, reducing the effective gravitational force.
Step 3: Hence gₑₓtₑff < g, and T = 2π√Lgₑₓtₑff increases.