Question

The time period of a simple pendulum is 2 sec. If its length is increased by 4 times, then its period becomes ___________

(a) 16 sec

(b) 8 sec

(c) 12 sec

(d) 4 sec

The question was posed to me at a job interview.

This question is from Wave Motion topic in section Waves of Engineering Physics I

Answer 1

Correct answer is (d) 4 sec

The explanation is: T∝√l, T^‘∝√4l

T^‘/T=2

T^‘=2T=2×2=4 sec.