What is the shape of the wavefront emitted by a point source in a uniform medium close to the source?
**Huygens principle** predicts shape of wavefront after propagation, for point source close spherical, far plane, after reflection from plane mirror spherical wave becomes spherical with centre mirrored, plane wave remains plane but direction changes angle of incidence equals reflection, after passing through thin prism plane wavefront tilts due to different path. A point source in a uniform medium emits spherical wavefronts, especially close to the source. 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 Spherical,
Ref: NCERT > Physics Book > Wave Optics > Wavefront and Huygens Principle