Question

LIght of wavelength 560 nm goes through a pinhole of diameter 0.20 mm and falls on a wall at a distance of 2.00 m. What will be th eradius of the central bright spot formed on the wall?

Answer 1

$\lambda =560nm=560\times {10}^{-9}m,d=0.20mm=2\times {10}^{-4}m,D=2m$
Since, $R=1.22\frac{\lambda D}{d}=1.22\times \frac{560\times {10}^{-9}\times 2}{2\times {10}^{-4}}=6.832\times {10}^{-3}M=0,683cm$
So diameter = 2R = 1.37 cm