Question

The time period of a simple pendulum at the centre of the earth is

• A. zero
• B. infinite
• C. less than zero
• D. none of these

Answer 1

Answer: (B)

Acceleration due to gravity at the center of the earth is zero.
$⟹g=0$
Time period of a simple pendulum is given by,
$T=2\pi \sqrt{\frac{1}{g}}$
$$\begin{gathered} ⟹T=2\pi \sqrt{\frac{1}{0}} \\ \therefore T=\infty \end{gathered}$$
So time period at the centre of the earth becomes infinite.