Question

A convex lens of focal length 25cm and a concave lens of focal length is 10cm are placed in closed contact with each other. calculate the lens power of this combination​

Answer 1

Answer:

f1 = 25 cm = 0.25 m

p1 = 1/f1 = 1/0.25 = 4D

f2 = -10 cm = -0.1m

p2 = 1/f2 = 1/-0.1 = -10D

Power of the combination:

P = p1 + p2

= 4D + (-10D)

= - 6 D