$A$ small object is placed $10\, cm$ in front of a plane mirror. If you stand behind the object $30\, cm$ from the mirror and look at its image,the distance focused for your eye will be........$cm$.

$A$ clock hung on a wall has marks instead of numbers on its dial. On the opposite wall there is a mirror,and the image of the clock in the mirror,if read,indicates the time as $8:20$. What is the actual time in the clock?

$A$ man runs towards a plane mirror at a speed of $15 \, m/s$. The speed of the image relative to the man is $...... \, m/s$.

$A$ monochromatic beam of light enters a square enclosure with mirrored interior surfaces at an angle of incidence $\theta_i(\neq 0)$ (see figure). For some value$(s)$ of $\theta_i$,the beam is reflected by every mirrored wall (other than the one with the opening) exactly once and exits the enclosure through the same hole. Which of the following statements about this beam is correct?

By what angle should $M_2$ be rotated,so that the light ray after reflection from both mirrors becomes horizontal? (The angle of incidence at mirror $M_1$ is $40^{\circ}$ and the angle between $M_2$ and the horizontal is $25^{\circ}$ as shown in the figure.)

The figure shows a cubical room $ABCD$ with the wall $CD$ as a plane mirror. Each side of the room is $3\,m$. $A$ camera is placed at the midpoint of the wall $AB$. At what distance should the camera be focused to photograph an object placed at $A$?