question_answer 8)

A beam of light,converges to a point P. A lensis placed in the path of the convergent beam 12 cm from P. At what point does the beamconverge if the lens is (a) a convex lens of focallength 20 cm, (b) a concave lens of focal length16cm ? 

Answer:

(a)The formation of image with and withoutthe placement of a convex lens shown, I? represents a virtual object with real image at I?.                   Using  or or i.e. image is formed 7-5 cm away from thelens and it is a real image. (b For a concave lens, the image formationis as shown. Using oror v = 48 cm i.e. the image formed is at a distance of 48cm from the lens and it is a real image.