Question

What is an example of total internal reflection at work? The intensity of light coming out of a thin plastic thread is same as that of light entering it. A ray of light entering a glass cube gets refracted. A ray of light in air hits a shiny surface and bounces off. A ray of light entering a ruby gets refracted. Physics

Answer 1

The intensity of light coming out of a thin plastic thread is same as that of light entering it.

Answer 2

Answer:

The intensity of light coming out of a thin plastic thread is same as that of light entering it.

Explanation:

As we know that in total internal reflection when light traveling in a denser medium and it then move out of that medium to a rarer medium then in that case the light has tendency to bend into the same medium again.

This phenomenon is known as total internal reflection

so here as per the formula of Snell's law we can say

$n_1 sin\theta_i = n_2 sin\theta_r$

now we know that

$n_1 > n_2$

so at limiting condition we know the angle of refraction is 90 degree

so we will have

$sin\theta_i = \frac{n_2}{n_1}$

so here correct answer will be

The intensity of light coming out of a thin plastic thread is same as that of light entering it.

as all other statements light is not moving from rare to denser medium in which total internal reflection is not possible