Unpolarized light of intensity $I_0$ is incident on the surface of a block of glass at Brewster's angle. In that case,which one of the following statements is true?

The velocity of light in air is $3 \times 10^8 \, ms^{-1}$ and that in water is $2.2 \times 10^8 \, ms^{-1}$. The polarising angle of incidence is.......$^o$

The angle of polarisation for any medium is $60^{\circ}$. What will be the critical angle for this medium?

When the angle of incidence is $60^{\circ}$ on the surface of a glass slab,it is found that the reflected ray is completely polarized. The velocity of light in glass is

$A$ solid glass sphere of refractive index $n=\sqrt{3}$ and radius $R$ contains a spherical air cavity of radius $\frac{R}{2}$,as shown in the figure. $A$ very thin glass layer is present at the point $O$ so that the air cavity (refractive index $n=1$) remains inside the glass sphere. An unpolarized,unidirectional and monochromatic light source $S$ emits a light ray from a point inside the glass sphere towards the periphery of the glass sphere. If the light is reflected from the point $O$ and is fully polarized,then the angle of incidence at the inner surface of the glass sphere is $\theta$. The value of $\sin \theta$ is

For a given medium,the polarizing angle is $60^{\circ}$. The critical angle for this medium is . . . . . .