Question

what is snails low and when does it fall​

Answer 1

Answer:

Snell's law fails when the light rays are incident normally on the surface of a refracting medium. In this case light passes undeviated from the surface, i.e. no refraction occurs. Refractive index is n = sin i/sin r = 0/0 = 0. But, n is not zero. Thus, Snell's law fails.