In the figure shown,for an angle of incidence $45^{\circ}$ at the top surface,what is the minimum refractive index $\mu$ needed for total internal reflection at the vertical face?

The speed of light in media $A$ and $B$ are $2.0 \times 10^{10} \, cm/s$ and $1.5 \times 10^{10} \, cm/s$ respectively. $A$ ray of light enters from medium $B$ to $A$ at an incident angle $\theta$. If the ray suffers total internal reflection,then:

If light travels a distance $x$ in $t_1 \, s$ in air and $10x$ distance in $t_2 \, s$ in a medium,the critical angle of the medium will be

$A$ spider and a fly are on opposite sides of the surface of a glass sphere. What is the maximum solid angle $\Omega$ within which the fly can be seen by the spider?
Given: The dimensions of the spider and the fly are very small with respect to the sphere. The refractive index of the glass is $\mu_g = \sqrt{2}$.

$A$ transparent block $A$ having refractive index $\mu_2 = 1.25$ is surrounded by another medium of refractive index $\mu_1 = 1.0$ as shown in the figure. $A$ light ray is incident on the flat face of the block with incident angle $\theta$ as shown in the figure. What is the maximum value of $\theta$ for which light suffers total internal reflection at the top surface of the block?

The figure shows a transparent block of side lengths $a$ and $a$. The third dimension of the block is negligible. $A$ point source $S$,which can emit light in all directions,can move inside the block. It is desired that no light from $S$ should pass through the segment $AB$. The region in which $S$ must be present to satisfy this condition is shown by the shaded region. Choose the correct option.