Light travels in two media $M_{1}$ and $M_{2}$ with speeds $1.5 \times 10^{8} \text{ m/s}$ and $2.0 \times 10^{8} \text{ m/s}$ respectively. The critical angle between them is.

$A$ glass prism $(\mu = 1.5)$ is dipped in water $(_a\mu_w = 4/3)$ as shown in the figure. $A$ light ray is incident normally on the surface $AB$. It reaches the surface $BC$ after being totally internally reflected at the surface $AC$,if:

Explain the experiment which demonstrates total internal reflection.

On the hypotenuse of a right-angled prism $(30^{\circ}-60^{\circ}-90^{\circ})$ with a refractive index of $1.50$,a drop of liquid is placed as shown in the figure. Light is allowed to fall normally on the short face of the prism. In order for the ray of light to undergo total internal reflection at the hypotenuse,what is the maximum value of the refractive index of the liquid?

Brilliance of diamond is due to

As shown,a narrow beam of light is incident onto a semi-circular glass cylinder of radius $R.$ Light can exit the cylinder when the beam is at the centre. When the beam is moved parallel to a distance $d$ from the central line,no light can exit the cylinder from its lower surface. Find the refractive index of the glass.