Question

Two diverging lenses with focal lengths of 0.30m and 0.50m are separated by 0.20m. A red jellybean rests on the axis of the lenses 0.50m in front of the first lens. What is the location of the final image with respect to the second lens?

Answer 1

here,

for the first lens

the object distance , do1 = - 0.5 m

the focal length , f1 = - 0.3 m

let the image distance be di1

using the lens fromula

1/f1 = 1/di1 - 1/do1

1/(-0.3) = 1/di1 - 1/(-0.5)

solving for di1

di1 = - 0.1875 m

for the second lens

the object distance , do2 = - (0.2 - di1) m = - 0.3875 m

the focal length , f2 = - 0.5 m

let the image distance be di2

using the lens fromula

1/f2 = 1/di2 - 1/do2

1/(-0.5) = 1/di2 - 1/(-0.3875)

solving for di2

di2 = - 0.218 m

the location of the final image with respect to the second lens is 0.218 m to the LEFT