Question

The radius of the half period zone is proportional to ___________

(a) The wavelength of light

(b) The square root of the frequency of light

(c) The square root of the wavelength light

(d) The frequency of light

This question was addressed to me during an interview.

This intriguing question comes from Fresnel Diffraction topic in section Optics of Engineering Physics II

Answer 1

Right choice is (c) The square root of the wavelength light

To explain I would say: We know that the formula for the radius of half period zone =\(\sqrt{nb\lambda}\), where n is a natural number. Thus, it is proportional to the square root of wavelength light and inversely proportional to the square root of the frequency of light.