Question

when dose no refraction take place​

Answer 1

Answer:

When angle of incidence θ

1

=0 or the refractive indices of both media are equal the light ray doesn’t deviate. It follows the same path and hence refraction doesn’t occur.

Answer 2

Refraction only occurs when the light travels from a denser to a rarer medium or vice versa. Even though it may be quantitatively explained by the Snell's law of refraction, however we need to consider the particle behavior of the light. The trajectory of the light depends on how its particles interact with those of the medium in which it travels. The rarer media have a sparse distribution of the constituent particles whereas the denser media have a dense distribution of particles so the attractive forces are more pronounced in the denser media and the light particles tend to move towards the normal, thus the refraction occurs. Therefore in a situation where there's no change in the light's medium, it doesn't refract.