Define normal shift. Obtain an expression for normal shift when an object in a denser medium is viewed from a rarer medium.

When Mars is viewed through a telescope it does not appear to twinkle. Comment.

What is refractive index of a medium?

"Ray of light travels from optically rarer medium to optically denser medium, it moves towards normal and when it travels from optically denser to optically rarer medium it moves away from the normal is known as refraction of light". Which of the following pentagon figures shows the correct refraction of light.

If the refractive index of water with respect to air (${}_{a }\mu _w$)  is $\frac{5}{3}$.  Calculate the refractive index of air with respect to water (${}_{w }\mu _a$).

What is the relation between the refractive index of water with respect to air $\left({}_{a }\mu _w\right)$, and the refractive index of air with respect to water $\left({}_{w }\mu _a\right)$.

When a ray of light is incident perpendicularly on a transparent glass slab, what will be its angle of deviation?

If a beam of red light and a beam of violet light are incident at the same angle on the inclined surface of a prism from air medium and produce angles of refraction $r \mathrm{and} v$ respectively. Which of the following is correct?