For what distance is ray optics is good approximation when the aperture is ( 4 ~mm ) and the wavelength of light is ( 400 ~nm ) ?

Step-by-step solution

Given, aperture, ( a=4 ~mm =4 10⁻³ ~m ); wavelength, ( =400 ~nm =400 10⁻⁹ ~m ) Distance, ( Z= a² = (4 10⁻³ )² 400 10⁻⁹ = 4 4 10⁻⁶ 400 10⁻⁹ ) ( Z=40 ~m ) Thus, for ( 40 ~m ) distance ray optics is in good approximation when the aperture is ( 4 ~mm ) and wavelength is ( 40 ~nm ).