When a beam of light is incident on a plane mirror,it is found that a real image is formed. The incident beam must be

$A$ ray reflected successively from two plane mirrors inclined at a certain angle undergoes a deviation of $300^o$. The number of observable images is:

$A$ man has a height of $180\, cm$ and his eyes are $10\, cm$ below the top of his head. He uses a plane mirror placed $1\, m$ away to see his full height from head to toe. What is the minimum required height of the plane mirror in $cm$?

$A$ tall man of height $6$ feet wants to see his full image. The required minimum length of the mirror will be ......... feet.

Two plane mirrors are kept on a horizontal table making an angle $\theta$ with each other as shown schematically in the figure. The angle $\theta$ is such that any ray of light reflected after striking both the mirrors returns parallel to its incident path. For this to happen,the value of $\theta$ should be (in $^{\circ}$)

$A$ 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?