Question

What is interference? Write the condition for path difference in case of constructive and destructive interference.

Answer 1

Interference is a phenomenon in which two waves, which are coherent to each other, superpose to form a resultant wave of greater, lower or same amplitude.

For the waves to superimpose constructively, path difference between the two waves must be integral multiple of wavelength of wave i.e. $\Delta x=n\lambda$

For the waves to superimpose destructively, path difference between the two waves must be half-integral multiple of wavelength of wave i.e. $\Delta x=(n+\frac{1}{2})\lambda$