Question

A plane wave-front propagating in a medium of refractive index 'μ₁' is incident on a plane surface making an angle of incidence (i). It enters into a medium of refractive index μ₂ (μ₂ > μ₁). Use Huygen's construction of secondary wavelets to trace the retracted wave-front. Hence verify Snell's law of refraction.

In single slit diffraction, explain why the maxima at θ = (n + 1/2)(λ/a) becomes weaker and weaker as n increases. State two important differences between interference and diffraction pattern.

A plane wavefront is incident on a surface separating two media of refractive indices n₁ and n₂ (> n₁). With the help of a suitable diagram, explain its propagation from the rarer to denser medium. Hence, verify Snell's law.

Identify electromagnetic waves which : (i) are used in radar system. (ii) affect a photographic plate. (iii) are used in surgery. Write their frequency range.