A convex lens of focal length 20 cm and a concave lens of focal length 10 cm are plac
Channel: Doubtnut
Date: 2020-06-28

A convex lens of focal length 20 cm and a concave lens of focal length 10 cm are placed 10 cm apart with their principal axes coinciding. A beam of light travelling parallel to the principal axis and having a beam diameter 5.0 mm, is incident on the combination. Show that the emergent beam is parallel to the incident one. Find the beam diameter of the emergent beam.