The observer at $O$ views two closely spaced spots on a vertical wall through an angled glass slab as shown. As seen by the observer,the spots appear

$A$ large glass slab $\left( \mu = \frac{5}{3} \right)$ of thickness $8 \, cm$ is placed over a point source of light on a plane surface. It is seen that light emerges out of the top surface of the slab from a circular area of radius $R \, cm$. What is the value of $R$? ....... $cm$

$A$ tiny air bubble in a glass slab $(\mu = 1.5)$ appears from one side to be $6 \, cm$ from the glass surface and from the other side,$4 \, cm$. The thickness of the glass slab is......$cm$

$A$ glass slab of thickness $20\, cm$ and refractive index $1.5$ is placed in front of a plane mirror. An object is placed at a distance of $40\, cm$ from the mirror in air. The position of the final image with respect to the mirror will be at a distance of:

One side of a glass slab is silvered as shown. $A$ ray of light is incident on the other side at an angle of incidence $i = 45^o$. The refractive index of the glass is $1.5$. The deviation of the ray of light from its initial path when it comes out of the slab is......$^o$.

$A$ point object is placed at a distance of $25 \, cm$ from a convex lens of focal length $20 \, cm$. If a glass slab of thickness $t$ and refractive index $1.5$ is inserted between the lens and the object,the image is formed at infinity. The thickness $t$ is....$cm$.