To get three images of a single object, one should have two plane mirrors at an angle of $...^\circ$.

Two plane mirrors are inclined at an angle of $72^{\circ}$. The number of images of a point object placed between them will be

Two plane mirrors ${M}_{1}$ and ${M}_{2}$ are at a right angle to each other as shown. $A$ point source $P$ is placed at distances of $a$ and $2a$ meters from ${M}_{1}$ and ${M}_{2}$ respectively. The longest distance between the images thus formed is: (Take $\sqrt{5} = 2.3$)

$A$ boy of height $1.5\, m$ with his eye level at $1.4\, m$ stands before a plane mirror of length $0.75\, m$ fixed on the wall. The height of the lower edge of the mirror above the floor is $0.8\, m$. Then:

Two plane mirrors are placed at an angle of $60^\circ$. $A$ horizontal light ray is reflected by the first mirror and then by the second mirror. The total deviation will be ........... $^\circ$.

$A$ plane mirror is approaching you at a speed of $10\,cm/sec$. You can see your image in it. At what speed will your image approach you in $cm/sec$?