If the length of a simple pendulum is equal to the radius of the earth, its time period will be

Options

A. `2pisqrt(R//g)`
B. `2pisqrt(R//2g)`
C. `2pisqrt(2R//g)`
D. infinite

Answer

B

Explanation

If the length of a simple pendulum in comparable to radius of earth R then `(1)/(1_(eff))=(1)/(R )+(1)/(1) Rightarrow 1_(eff)=(R )/(2)`
`T=2pisqrt((1_(eff))/(g))=2pisqrt(R )/(2g)`