In the figure shown,how many images of the star will an observer at $O$ see?

$A$ ray of light makes an angle of $10^o$ with the horizontal above it and strikes a plane mirror which is inclined at an angle $\theta$ to the horizontal. The angle $\theta$ for which the reflected ray becomes vertical is......$^o$

$A$ cubical room is made of mirrors. An insect is moving along the diagonal on the floor such that the velocity of the image of the insect on two adjacent wall mirrors is $10 \, cm \, s^{-1}$. The velocity of the image of the insect in the ceiling mirror is:

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

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

When a plane mirror is rotated through an angle $\theta$,the reflected ray turns through an angle $2\theta$. What happens to the size of the image?