Question

A concave mirror of focal length 'f1' is placed at a distance of 'd' from a convex lens of focal length 'f2'. a beam of light coming from infinity and falling on this convex lens-concave mirror combination returns to infinity. the distance 'd' must equal :-

Answer 1

Answer:

A beam of light coming from infinity and falling on this convex lens, concave mirror combination returns to infinity. Solution: The image form at the focus , when light comes from infinity . ... Hence, it is require that concave mirror should be placed 2× focus of concave mirror from first image