Question

The critical angle for total internal reflection occurs when:___________.

Answer 1

Answer:

b) the refracted ray has an angle of 90 degrees

Explanation:

The angle of incidence is measured with respect to the normal separation of the media. The critical angle for total internal reflection occurs is:

$\theta=arcsin(\frac{n_2}{n_1})$

Here $n_2$ and $n_1$ are the refractive index of the mediums. This equation is an application of Snell's law, for the case where  the refracted ray has an angle of $90^\circ$.