Question

For what distance is ray optics a good approximation when the aperture is `3 mm` wide and wavelength is `500 nm` ? (NCERT Solved Example)

Answer 1

Here, `a = 3 mm = 3 xx 10^(-3)m`,
`lambda = 500 nm = 5 xx 10^(-7) m`
Fresnel distance, `Z_(F) = (3 xx 10^(-3))^(2)/(5 xx 10^(-7)) = 18m`