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

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

$A$ beam of light from a source $L$ is incident normally on a plane mirror fixed at a certain distance $x$ from the source. The beam is reflected back as a spot on a scale placed just above the source $L$. When the mirror is rotated through a small angle $\theta$,the spot of the light is found to move through a distance $y$ on the scale. The angle $\theta$ is given by

Light rays fall on a plane mirror and form a real image. Therefore,the incident rays are:

The rear window of a car has a size of $120 \, cm \times 45 \, cm$. The driver sits at a distance $L = 2 \, m$ from the rear window. What should be the minimum size of a flat mirror,hanging at a distance of $0.5 \, m$ in front of the driver,so that he has the best view of the road situation behind the car?

$A$ plane mirror rotating at an angular velocity of $3 \; rad/s$ reflects a light beam. The angular velocity of the reflected beam is ........ $rad/s$.