Question

Give the condition for constructive and destructive interference in terms of phase difference and path difference.

Answer 1

$Constructive$ interference occurs when path difference is an integral multiple of wavelength that is $\Delta x=n\lambda$

And , phase difference, $\varphi =\frac{2\pi }{\lambda }\Delta x=2n\pi$

$Destructive$ interference occurs when path difference is an odd integral multiple of half of the wavelength that is $\Delta x=(2n+1)\frac{\lambda }{2}$

And , phase difference, $\varphi =\frac{2\pi }{\lambda }\Delta x=(2n+1)\pi$