Name the lens which always forms a virtual image of an object.

It is desired to obtain an erect image of an object, using concave mirror of focal length of 12cm.
Where will the image of this object be, if it is placed 24cm in front of the mirror? Draw ray diagram for this situation also to justify your answer.
Show the positions of pole, principal focus and the centre of curvature in the above ray diagrams.

With the help of a ray diagram explain why a concave lens diverges the rays of a parallel beam of light.

An object of height 4.0cm is placed at a distance of 30cm from the optical centre ‘O’ of a convex lens of focal length 20cm. Draw a ray diagram to find the position and size of the image formed. Mark optical centre ‘O’ and principal focus ‘F’ on the diagram. Also find the approximate ratio of size of the image to the size of the object.

The focal length of a lens is +150mm. What kind of lens is it and what is its power?

A ray of light is incident on a convex mirror as shown. Redraw the diagram and complete the path of this ray after reflection from the mirror. Mark angle of incidence and angle of reflection on it.

If an object is placed at a distance of 8cm from a concave mirror of focal length 10cm, discuss the nature of the image formed by drawing the ray diagram.

To construct ray diagram we use two light rays which are so chosen that it is easy to know their directions after reflection from the mirror. List these two rays and state the path of these rays after reflection. Use these rays to locate the image of an object placed between centres of curvature and focus of a concave mirror.

Why does a beam of light when it enters glass at an angle? Why does it not bend if it inters the glass at right angles?