$A$ ray of light travelling in a transparent medium of refractive index $\mu$ falls on a surface separating the medium from air at an angle of incidence of $45^o$. For which of the following values of $\mu$ can the ray undergo total internal reflection?

$A$ point source $S$ is placed at the bottom of a transparent block of height $h = 10 \ mm$ and refractive index $n_B = 2.72$. It is immersed in a liquid of lower refractive index $n_L$ as shown in the figure. It is found that the light emerging from the block into the liquid forms a circular bright spot of diameter $D = 11.54 \ mm$ on the top surface of the block. The refractive index of the liquid $n_L$ is:

Assertion: The air bubble shines in water.
Reason: Air bubble in water shines due to refraction of light.

$A$ beam of light consisting of red,green,and blue colors is incident on a right-angled prism as shown. The refractive indices of the material of the prism for red,green,and blue wavelengths are $1.39, 1.44$,and $1.47$ respectively. The prism will:

$A$ ray of light is incident on the hypotenuse of a right-angled prism after travelling parallel to the base inside the prism. If $\mu$ is the refractive index of the material of the prism, the maximum value of the base angle for which light is totally reflected from the hypotenuse is

In an optical fibre,the refractive index of the inner part (core) is $1.68$ and the refractive index of the outer part (cladding) is $1.44$. The numerical aperture of the fibre is ........