$A$ 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 $^o$)

Two mirrors are inclined at an angle $\theta$ as shown in the figure. $A$ light ray is incident parallel to one of the mirrors. The ray will start retracing its path after the third reflection if $\theta = ........$

$A$ small object of size $10\, cm$ is placed in front of a plane mirror. $A$ person stands $30\, cm$ behind the object and views the image of the object. At what distance (in $cm$) from the person's eyes must the image be focused?

Light of wavelength $5000 \,\mathring{A}$ falls on a plane reflecting surface. What are the wavelength and frequency of the reflected light? For what angle of incidence is the reflected ray normal to the incident ray?

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

The separation between the screen and a plane mirror is $2r$. An isotropic point source of light is placed exactly midway between the mirror and the screen. Assume that the mirror reflects $100\%$ of the incident light. Then the ratio of illuminances on the screen with and without the mirror is