What are the types of mirrors?

$A$ point source of light $S$ at a distance $d$ from the screen $A$ produces light intensity $I_0$ at the centre of the screen. If a completely reflecting mirror $M$ is placed at a distance $d$ behind the source as shown in the figure,treating the object and its image as incoherent with each other,find the intensity at the centre of the screen.

When a plane mirror is placed horizontally on a level ground at a distance of $60 \ m$ from the foot of a tower,the top of the tower and its image in the mirror subtend an angle of $90^\circ$ at the eye. The height of the tower will be.....$m$.

$A$ small plane mirror is placed at the centre of a spherical screen of radius $R$. $A$ beam of light is falling on the mirror. If the mirror makes $n$ revolutions per second,the speed of the reflected light spot on the screen will be:

$A$ mirror is placed at a distance of $60 \ m$ from the base of a tower. The angle between the top of the tower and the top of its image is $90^o$. Find the height of the tower in $m$.

Assertion : Plane mirror may form real image.
Reason : Plane mirror forms virtual image,if object is real.