# 1. Two particles executing SHM of same frequency meet at = A/2, while moving in opp directions, What is the phase difference between them? 2.Two pendulum of length 1.21m and 1m start vibrating. At some instant the two are in the mean position in same phase. After how many vibrations of the longer pendulum will they be in the same phase again?

SAGAR SINGH - IIT DELHI
879 Points
12 years ago

Dear student,

Its the difference between some reference point in 2 waves. Its how much one wave is shifted from the other. For eg. at the origin, if one wave's displacement is zero and the other one has some displacement, then there is a shift, which is their phase difference. For eg. sine wave is zero at the origin, but cos wave is not zero at the origin, its zero at pi/2. So the phase difference is pi/2. Infact, cos wave is just the sine wave phase-shifted.

If two waves have zero phase difference, then their crests occur at the same time and so do their troughs. Its like moving together. They will add up (constructive interference).

All the best.

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