Question

A neutral pendulum oscillates in an uniform electric field as shown in figure. If a positive charge is given to the pendulum then its time period :

• A. will increase
• B. will decrease
• C. will remain constant
• D. will first increase then decrease

Answer 1

The correct option is A will increase

When a positive charge q is given to the pendulum, the effective acceleration will reduce from $g$ to $g^{\prime }=g-\frac{qE}{m}$.
Time period , $T=2\pi \sqrt{l/g^{\prime }}$
As $g^{\prime }$ decreases so time period will increase.