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
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?
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)
Distinguish between a real and a virtual image.
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.