Question

Two converging lenses are separated by 29.00 cm. The focal length of each lens is 17.00 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

Lens equation is given by

u is the object distance, v is the image distance and f is the focal length.

Let us first find out the image of the object due to the lens on the left.

We will assume cartesian sign convention where distances measured opposite to the light propagation is negative.

The object is placed 32 cm left of the left lens i.e.,

This is a converging lens; Hence focal length is positive.

So,

The plus sign indicates that the image is formed 36.27 cm right of the left lens.

This image will become the object of the 2nd lens placed on the right.

Separation between the two lens is L=29 cm

So, object distance for the right lens is

Using Lens equation:

So, the final image will be 5.09 cm to the right of the right lens.