Question

Select the most appropriate word from the given box and fill in the following blanks.

normal 48.6° ray red refractive index vacuum 41° refraction 2.3

The critical angle for glass is ______ and for water is ______.

Answer 1

The critical angle for glass is 41° and for water is 48.6°.

Explanation:

The critical angle is the angle of incidence in the denser medium for which the angle of refraction in the rarer medium becomes $90^\circ$. For a glass-air interface it is approximately $41^\circ$, and for a water-air interface it is about $48.6^\circ$.