Question

A simple pendulum of period $T$ has a metal bob which is negatively charged. If it is allowed to oscillate above a positively charged metal plate, its period will

• A. remain equal to $T$
• B. be less than $T$
• C. be greater than $T$
• D. be infinite

Answer 1

Answer: (B)

When a negatively charged pendulum oscillates over a positively charged plate, then effective value of $g$ increases, so according to $T=2\pi \sqrt{\frac{l}{g}},T$ decreases.