What type of mirror is used to obtain a real image?

Which of the following ray diagrams is correct for the ray of light incident on a lens shown in the figure?

Which type of image cannot be obtained by a concave mirror?

What happens when a light ray incident normally on the surface of a glass slab enters from air into the glass?

Give one use of a concave lens.

$A$ pencil when dipped in water in a glass tumbler appears to be bent at the interface of air and water. Will the pencil appear to be bent to the same extent,if instead of water we use liquids like kerosene or turpentine? Support your answer with reason.