The minimum area of the disc needed to cut off all the light coming out of water $\left(\mu_{w} = \frac{4}{3}\right)$ from a point source of light placed $7 \ m$ below the water surface is: (in $\pi \ m^2$)

In the diagram shown,a ray of light is incident on the interface between medium $1$ and $2$ at an angle slightly greater than the critical angle. The light undergoes total internal reflection at this interface. After that,the light ray falls on the interface of medium $1$ and $3$,and again it undergoes total internal reflection. Which of the following relations should hold true?

$A$ ray of light refracts from medium $1$ into a thin layer of medium $2$, crosses the layer, and is incident at the critical angle on the interface between medium $2$ and $3$ as shown in the figure. If the angle of incidence of the ray is $\theta$, the value of $\theta$ is

Light is incident from a medium into air at two possible angles of incidence $(A) \ 20^o$ and $(B) \ 40^o$. In the medium,light travels $3.0 \ cm$ in $0.2 \ ns$. The ray will

$A$ light ray is incident normally on one face of a right-angled prism and travels parallel to the base inside the prism. If the refractive index of the prism is $\mu$,what should be the angle $\alpha$ that the hypotenuse makes with the base so that the ray undergoes total internal reflection at the hypotenuse?

$A$ light ray traveling in a glass medium is incident on a glass-air interface at an angle of incidence $\theta$. The reflected $(R)$ and transmitted $(T)$ intensities,both as functions of $\theta$,are plotted. The correct sketch is: