1-9 Interference of waves

Two sinusoidal waves y₁(x,t) and y₂(x,t)

moving in the same medium interfere to produce the resultant wave y_res(x,t)

We say that the two waves interfere destructively if the resultant wave has an amplitude of zero, which is the minimum possible amplitude the resultant wave can have. Thus destructive interference occurs when

 

Destructive interference occurs when the phase difference between wave 1 and wave 2 is an odd integer multiple of p,or equivalently, the path difference between them is an odd integer multiple of l/2.

We say that the two waves interfere constructively if the resultant wave has an amplitude of 2y_m, which is the maximum possible amplitude the resultant wave can have. Thus constructive interference occurs when

 

Constructive interference occurs when the phase difference between wave 1 and wave 2 is an integer multiple of 2p,or equivalently, the path difference between them is an integer multiple of l.