Question

11.
2) 2f
3) f/2
LEVEL - 3
Two lens of powers -1.5 D and +2.75 D are kept in contact. Find the focal
length of the combination.
1) 0.2 m
4) 0.83 m
2) 0.03 m
3) 1.6 m​

Answer 1

net power P = -1.5 + 2.75

P = +1.25 D

focal length of combination be f

f = 1/P

f = 1/1.25

f = 0.8