Power of a plane mirror is . . . . . .

$A$ light bulb is placed between two plane mirrors inclined at an angle of $60^{\circ}$. The number of images formed is:

$A$ ray gets successively reflected from two mirrors inclined at an angle of $40^o$. If the angle of incidence on the first mirror is $30^o$,then the net deviation of this ray after two reflections is: (in $^o$)

The angle made by the incident ray of light with the reflecting surface is called:

$A$ man of height $170 \, cm$ wants to see his complete image in a plane mirror (while standing). His eyes are at a height of $160 \, cm$ from the ground. Which of the following statements are correct?
$(a)$ Minimum length of mirror is $80 \, cm$
$(b)$ Minimum length of mirror is $85 \, cm$
$(c)$ Bottom of the mirror should be at a height $80 \, cm$
$(d)$ Bottom of the mirror should be at a height $85 \, cm$

$A$ laser beam is incident on a plane mirror at some angle and results in a reflected beam. The mirror is now rotated by an angle $\delta$ while the direction of the incident laser beam is kept the same. The angle between the new reflected beam and the reflected beam before the mirror was rotated is