Physics
What are the three principal rays that are drawn to construct the ray diagram for the image formed by a lens? Draw diagrams to support your answer.
Answer
(i) A ray of light incident at the optical centre O of the lens passes undeviated through the lens.
Convex Lens
Concave Lens
(ii) A ray of light incident parallel to the principal axis of the lens, after refraction passes through the second focus F2 (in a convex lens) or appears to come from the second focus F2 (in a concave lens), respectively.
Convex Lens
Concave Lens
(iii) A ray of light passing through the first focus F1 (in a convex lens) or directed towards the first focus F1 (in a concave lens), emerges parallel to the principal axis after refraction, respectively.
Convex Lens
Concave Lens
Related Questions
A lens forms an upright and magnified image of an object.
(a) Name the lens.
(b) Draw a labelled ray diagram to show the image formation.
In each of the following cases, where must an object be placed in front of a convex lens so that the image formed is,
(a) at infinity,
(b) of same size as the object,
(c) inverted and enlarged,
(d) upright and enlarged?
Distinguish between a real and a virtual image.
In the diagrams below, XX' represents the principal axis, O the optical centre and F the focus of the lens. Complete the path of the rays A and B as they emerge out of the lens.
(a)
(b)
