For what distance is ray optics a good approximation when the aperture is 4 mm wide and the wavelength is 500 nm?

Options

A. 22 m
B. 32 m
C. 42 m
D. 52 m

Answer

B

Explanation

Fresnel distance, `z_(F)=(a^(2))/(lambda)=((4xx10^(-3))^(2))/(500 xx 10^(-9))`
` :. z_(F)=32m`