Question

A screen is placed at a distance of 100𝑐𝑚 from a circular hole illuminated 

by a parallel beam of light of wavelength 6400Å. Compute the radius of 

fourth half period zone.

Answer 1

Answer

the radius of

n th half period zone

$R_n=\sqrt{nd\lambda}$

$=\sqrt{4\times1\times6400\times10^{-10}}\\=16\times10^{-5}m\\=0.016cm$