# Working with a thins lens

Work this problem using the thin-lens equation:

A diverging lens with focal length of 25 cm is used to view a postage stamp 50 cm from the lens. (a) How far from the lens does the stamp appear? (b) What is the magnification of the image? Work this problem by ray tracing?

I need to see each step and formula to solve this question. Please assume I know nothing because this would be the correct assumption. :)

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## SOLUTION This solution is **FREE** courtesy of BrainMass!

The thin lens equation is

(1/object distance) + (1/image distance) = (1/focal length)

As we are using a diverging (concave) lens, the focal length is considered negative

here object distance, o = 50cm, focal length = -25cm

so, 1/50 + 1/i = -1/25

1/i = -(1/50 + 1/25) = 0.02+0.04 = -0.06

or i = -16.67cm

So the image at 16.67 cm on the same side of the object.

The magnification of the lens is given by: M = - (image distance/object distance)

= -(-16.67/50)

= 0.3334

o we will see a small image of the stamp on the same side of the object

Â© BrainMass Inc. brainmass.com December 24, 2021, 6:00 pm ad1c9bdddf>https://brainmass.com/physics/lenses/working-with-a-thins-lens-85769