A beam of light converges at a point P. Now a lens is placed in the path of the convergent beam 12 cm from P. At what point does the beam converge if the lens is (a) a convex lens of focal length 20 cm, and (b) a concave lens of focal length 16 cm?
Open in App
Verified by Toppr
(a). According to the given case, object is virtual, u=+12cm
The focal length of the convex lens is f=+20cm.
Using lens equation, v1−u1=f1
(b). Now the focal length of the concave lens, f=−16cm
Solve any question of Ray Optics and Optical Instrument with:-