Snell S Law Of Refraction — the NEET Physics formula with its derivation, variables, validity constraints and worked solver.
Snell's Law of Refraction Applies to the refraction of light at the boundary between two isotropic transparent media. Fermat's Principle of Least Time Huygens' Principle (Wavefront continuity) Media must be isotropic and homogeneous. Light must be monochromatic (ignoring dispersion). Angles are measured with respect to the normal. Measuring angle of incidence/refraction from the surface instead of the normal. Confusing relative refractive index (1mu2 vs 2mu1). Applying it where Total Internal Reflection occurs without checking critical angle.