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# Problem: A lens with a focal length of 25 cm is placed 45 cm in front of a lens with a focal length of 5.0 cm. a. How far from the second lens is the final image of an object infinitely far from the first lens? b. Is the image in part a in front of or behind the second lens?

###### FREE Expert Solution

Lens equation:
$\overline{)\frac{\mathbf{1}}{{\mathbit{s}}_{\mathbit{o}}}{\mathbf{+}}\frac{\mathbf{1}}{{\mathbit{s}}_{\mathbit{i}}}{\mathbf{=}}\frac{\mathbf{1}}{\mathbit{f}}}$

a.

For the first lens, the object is at infinity. The image is formed at the focal point of the first lens.

The distance of the image from the second lens is:

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###### Problem Details

A lens with a focal length of 25 cm is placed 45 cm in front of a lens with a focal length of 5.0 cm.

a. How far from the second lens is the final image of an object infinitely far from the first lens?

b. Is the image in part a in front of or behind the second lens?