$A$ 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:

$PQR$ is a right-angled prism with other angles as $60^o$ and $30^o$. The refractive index of the prism is $1.5$. $PQ$ has a thin layer of liquid. Light falls normally on the face $PR$. For total internal reflection at the face $PQ$,the maximum refractive index of the liquid is

$A$ ray of light travels from a denser medium $(\mu)$ to air. The angle of incidence is denoted by $i$ and the angle of deviation by $D$. Let $C = \sin^{-1}(1/\mu)$. Which of the following graphs is correct?

$A$ rod of glass $(\mu = 1.5)$ with a square cross-section is bent into the shape shown in the figure. $A$ parallel beam of light falls on the plane flat surface $A$ as shown. If $d$ is the width of a side and $R$ is the radius of the inner circular arc,what is the maximum value of $\frac{d}{R}$ such that the light entering the glass slab through surface $A$ emerges from the glass through $B$?

The phenomenon of total internal reflection is observed when the angle of incidence is

$A$ ray of light incident normally on an isosceles right-angled prism travels as shown in the figure. The least value of the refractive index of the prism must be