$A$ 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......$cm$

$A$ small pin fixed on a table top is viewed from above from a distance of $50 \, cm$. By what distance would the pin appear to be raised if it is viewed from the same point through a $15 \, cm$ thick glass slab held parallel to the table? Refractive index of glass $= 1.5$. Does the answer depend on the location of the slab?

The time required for the light to pass through a glass slab (refractive index $= 1.5$) of thickness $4 \,mm$ is ($c = 3 \times 10^{8} \,m/s$, speed of light in free space).

If the velocity of light in vacuum is $3 \times 10^{8} \text{ m/s}$, the time taken (in nanoseconds) to travel through a glass plate of thickness $10 \text{ cm}$ and refractive index $1.5$ is:

$A$ light ray enters a rectangular glass slab of refractive index $\sqrt{3}$ at an angle of incidence of $60^{\circ}$. It travels a distance of $5 \, cm$ inside the slab and emerges out. What is the perpendicular distance between the incident and emergent ray?

$A$ 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....$cm$.