Question

A lens with power 5D is made in contact with another lens and the combined focal length is 12cm. Power of the component lens is

Answer 1

Answer:

Explanation:

Focal length of lens X = 15 cm = 0.15 m

Power of lens X

= 1/0.15

= 100/15 = 20/3

= +6.66 D

Power of Combination of lenses X & Y = power of lens X + power of lens Y

56.66+ Power of lens Y

Power of lens Y

= 5-6.66 = -1.66 D

(a) Focal length = 1/Power

f = 1/(-1.66)

f = -0.6 m

f = -60 cm

(b) As the focal length of lens Y is negative hence the nature of lens is Diverging lens, that is Concave lens.