The formation of an image by a lens is due to which optical phenomenon?

An incident ray falls normally on a glass slab. What is the angle of refraction (in $°$)?

When does Snell's law fail?

You are given water,mustard oil,glycerine,and kerosene. In which of these media would a ray of light incident obliquely at the same angle bend the most?

What is the absolute refractive index of common glass?

$(a)$ State the laws of refraction.
$(b)$ $A$ ray of light enters from a medium $A$ into a slab made up of a transparent substance $B$ (as shown in the figure). The refractive indices of medium $A$ and $B$ are $2.42$ and $1.65$ respectively. Complete the path of the ray of light until it emerges out of the slab.