Correct Option: D

The time period ‘T’ of a simple pendulum is given
by T = 2
1
p
g , where l is the length and g is the acceleration due to gravity. Let us suppose g be to be a constant, then T =21 p . So the time period of a pendulum is directly proportional to the square root of its length. So, if the length increases, its time period also increase. It means that it takes longer to complete one oscillation. So when its length is halved, its time period is decreased by a factor of 2 .