When an object is placed between two parallel mirrors,the number of images formed is:

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 $^{\circ}$)

$A$ small plane mirror is placed at the center of a spherical screen of radius $R$. Light rays are incident on the mirror. If the mirror is rotated at a frequency of $n$ revolutions per second,what will be the speed of the reflected light spot on the screen?

$A$ thick plane mirror shows a number of images of the filament of an electric bulb. Of these,the brightest image is the

$A$ man is $180\,cm$ tall and his eyes are $10\,cm$ below the top of his head. In order to see his entire height from toe to head,he uses a plane mirror kept at a distance of $1\,m$ from him. The minimum length of the plane mirror required is.....$cm$.

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