Two lenses of focal length 4.5cm and 1.5cm are placed at a certain distance apart, calculate the distance between the lenses if they form an achromatic combination

Question

asked Nov 24, 2021 15.5k views

1 Answer

Michal Fapso · Answer 1 · 2021-11-30T07:18:58+0000

3.0cm

For lenses in an achromatic combination, the following condition holds, assuming the two lenses are of the same materials;

d =
(f_1 + f_2)/(2) ---------(i)

Where;

d= distance between lenses

f₁ = focal length of the first lens

f₂ = focal length of the second lens

From the question;

f₁ = 4.5cm

f₂ = 1.5cm

Substitute these values into equation (i) as follows;

d =
(4.5+1.5)/(2)

d =
(6.0)/(2)

d = 3.0cm

Therefore, the distance between the two lenses is 3.0cm