Question

To construct ray diagrams, two rays of light are generally so chosen that it is easy to determine their directions after reflection from a mirror. Choose two such rays and state the path / direction of these rays after reflection from a concave mirror. Use these two rays to find the position and nature of the image of an object placed at a distance of 8 cm from concave mirror of focal length 12 cm.

Answer 1

Ray which are choose to construct ray diagram for reflection are:

(i) A ray parallel to the principal axis and 

(ii) A ray passing through the centre of curvature of a concave mirror or appear to pass through the centre of curvature of convex mirror.

Path of these rays after reflection:

(i) After reflection, it will pass through the principal focus of a concave mirror or appear to diverge in case of a convex mirror.

(ii) After reflection, it is reflected back along the same path.

v=+ve, So image is virtual and is formed at a distance of 24 cm behind the mirror.