What is the shape of the wavefront after a plane wave passes through a thin prism?
**Wavefront** is locus of points in same phase, spherical from point source, plane at large distance because radius large, Huygens principle every point on wavefront acts as secondary source of wavelets, new wavefront envelope of secondary wavelets, allows prediction of new wavefront shape from known wavefront, explains reflection and refraction. A plane wave passing through a thin prism gets delayed variably, resulting in a tilted plane wavefront. Using Δ = d sinθ, y = n λ D/d, a sinθ = n λ, I = I₀ cos²θ, n = c/v, sinC = 1/n, λ' = λ/n and A = 2a cos(φ/2), calculation gives Tilted plane, illus
Ref: NCERT > Physics Book > Wave Optics > Wavefront and Huygens Principle