Question

A convex lens of focal length 20 cm is placed in contact with a concave lens of focal
length 50 cm. Find the power of the combination (in diopter)​

Answer 1

Answer:

-5 D

Explanation:

Pconvex1=50100=+2D

Pconcave1=−50100=−2D

Pconcave2=−20100=−5D

Peq=−2−5+2

        =−5D