Beams of light are incident through the holes $A$ and $B$ and emerge out of the box through the holes $C$ and $D$ respectively,as shown in the figure. Which of the following could be inside the box?

The laws of reflection are true only for plane mirrors and not for curved mirrors.

For which type of mirror will the image always be erect,regardless of the distance at which the object is placed?

$(a)$ 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.

The following table gives the values of refractive indices of a few media:

$S.No.$	$1$	$2$	$3$	$4$	$5$
Medium	Water	Crown glass	Rock salt	Ruby	Diamond
Refractive index	$1.33$	$1.52$	$1.54$	$1.71$	$2.42$

Use this table to give an example of $(i)$ a medium pair so that light speeds up when it goes from one of these media to another. $(ii)$ a medium pair so that light slows down when it goes from one of these media to another.

An object is brought towards a concave mirror. How does the position and size of the image change?