To get three images of a single object, the angle between the two plane mirrors should be (in $^{\circ}$)

With reference to the figure shown below, match the following:

$(a)$ Angle of reflection	$(i)$ $60^\circ$
$(b)$ Value of $\alpha$	(ii) $120^\circ$
$(c)$ Angle of deviation	(iii) $30^\circ$

$A$ point source is placed at coordinates $(0,1)$ in the $xy$-plane. $A$ ray of light from the source is reflected on a plane mirror placed along the $X$-axis and perpendicular to the $xy$-plane. The reflected ray passes through the point $(3,3)$. What is the path length of the ray from $(0,1)$ to $(3,3)$?

The figure shows two rays $A$ and $B$ being reflected by a mirror and emerging as $A'$ and $B'$. The mirror

The focal length of a plane mirror is .......

$A$ light beam is being reflected by using two mirrors,as in a periscope used in submarines. If one of the mirrors rotates by an angle $\theta$,the reflected light will deviate from its original path by the angle