A simple pendulum has a time period T1 when on earth's surface and T2 when taken to a height R above the earth's surface, where R is the radius of the earth. The value of T2T1 is
2
If acceleration due to gravity is g at the surface of earth then at height R it value becomes g′=g(RR+h)2=g4
T1=2π√lg and T2=2π√lg4 ∴T2T1=2