Question

Why we cant see rainbow if angle of incidence is lesser than critical angle of incidence?​

Answer 1

Answer:

When the angle of incidence is less than the critical angle both reflection and refraction occur . No new thing. But when the angle becomes equal to critical angle, then the refracted ray becomes parallel to the surface or angle of refraction becomes 90°.

Because indices of refraction depend on wavelength, the critical angle (and hence the angle of total internal reflection) will vary slightly with wavelength and, therefore, with colour. At all angles less than the critical angle, both refraction and reflection occur in varying proportions.

Answer 2

Answer:

When the angle of incidence is less than the critical angle both reflection and refraction occur . No new thing. But when the angle becomes equal to critical angle, then the refracted ray becomes parallel to the surface or angle of refraction becomes 90