Question

Q2
A convex lens of focal length 40cm is placed in contact with a convex lens of local length 25cm What is the power of the combination?​

Answer 1

Answer:

A convex lens of focal length 40 cm is in contact with a concave lens of focal length 25 cm. The power of the combination is. Solution : P=1f=1f1+1f2=10.4+1-0.25=-1.5diopter

Answer 2

Convex lens:
F=40 cm
P=100/f P= 100/40=+2.5D
Concave lens
F=25cm
P=-100/f P=-100/25=-4D
Power of the combination
=-2.5D+(-4D)
=+2.5D-4D
=-1.5D