$A$ ray of light is incident on a plane mirror at an angle of $30^\circ$. The deviation produced in the ray is....$^\circ$.

The focal length of a plane mirror is:

$A$ ray of light is reflected by a plane mirror. $\hat{e}_0$, $\hat{e}$ and $\hat{n}$ be the unit vectors along the incident ray, reflected ray and the normal to the reflecting surface respectively. Which of the following gives an expression for $\hat{e}$?

$A$ light bulb is placed between two plane mirrors inclined at an angle of $60^{\circ}$. The number of images formed is:

$A$ 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.....$cm$.

The image of an object $O$ due to reflection from the surface of a lake is elongated due to the ripples on the water surface caused by a light breeze. This is because the ripples act as tilted mirrors as shown below. Consider the case,where $O$ and the observer $E$ are at the same height above the surface of the lake. If the maximum angle that the ripples make with the horizontal is $\alpha$,then the angular extent $\delta$ of the image will be