In given set up,
focal length of mirror = 20 cm,
focal length of lens = 15 cm
and separation of mirror and lens = 40 cm.
A point source S of light ‘S’ is placed on principal axis at distance d from lens.
If the final beam comes out parallel to the principal axis, then value of d is
(a) 4 cm
(b) 8 cm
(c) 12 cm
(d) 16 cm
