Question

Two converging lenses are separated by 24.00 cm. The focal length of each lens is 15.00 cm. An object is placed 32.00 cm to the left of the lens that is on the left. Determine the final image distance relative to the lens on the right.

Answer 1

Focal length of the lens, f = 15.0 cm

Object position for the first lens, fo = 32.0 cm

In this arrangement, the image of the first lens will become the object for the second lens.

So, first we will find the image position of the first lens -

Use the lens formula,

1/f = 1/do + 1/di

=> 1/15.0 = 1/32.0 + 1/di

=> 1/di = 0.0667 - 0.0312 = 0.0355

=> di = 28.17 cm

Now, given that the distance between lenses is 32.0 cm

So,

32.0 - 28.17 = 3.83 cm will be 'do' for the second lens.

Use lens formula,

1/15.0 = 1/3.83 + 1/di

=> 1/di = 0.0667 - 0.2611 = -0.1944

=> di = -5.14 cm

Therefore, the final image will be 5.14 cm left of the right hand lens.

The image will be virtual and enlarged, because the object was inside the focal length of the second lens.

(Answer)