# Problems with Optics and Lenses

Hi. Can someone please show me how to do the following problem? Thank you.

"A magnifying glass is a single convex lens with a focal length of f = +11.0 cm. (Assume the person using the magnifying glass has a near point of 25 cm and the magnifying glass is directly in front of the person's eyes.)

(a) What is the angular magnification when this lens forms a (virtual) image at -infinity. (I've done this one. The answer is 2.27. But I can't figure out how to do the others.)

(b) How far from the object should the lens be held?

(c) What is the angular magnification when this lens forms a (virtual) image at the person's near point?

(d) How far from the object should the lens be held in this case?

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#### Solution Preview

a) That is correct: M = 25 / 11 = 2.27

b) For the best viewing, the object should be placed at the focal point so that the virtual image is at infintiy. That ...

#### Solution Summary

The solution provides step-by-step calculations for various optics and lens questions.