Register to reply

Lens magnification question

by Linus Pauling
Tags: lens, magnification
Share this thread:
Linus Pauling
Feb12-10, 12:45 PM
P: 190
1. Your task in physics laboratory is to make a microscope from two lenses. One lens has a focal length of 2.8 cm, the other 1.1 cm. You plan to use the more powerful lens as the objective, and you want the eyepiece to be 15 cm from the objective.

What is the magnification of your microscope?

2. Thin lens equation
M_obj = -s'/s
M_eye = ???

3. In part one I solved for s, and s = 1.2cm. The more powerful lens is the one with f = 1.1, and s' = 13.2. Thus, the magnification of the objective lens should be -s'/s = -13.2/1.2 = -11. Is that correct? Also, what do I sue for the magnification of the eye? I know that I have to mutiply those two values to obtain my final answer.
Phys.Org News Partner Science news on
Scientists develop 'electronic nose' for rapid detection of C. diff infection
Why plants in the office make us more productive
Tesla Motors dealing as states play factory poker
Linus Pauling
Feb12-10, 08:03 PM
P: 190
This one's really killing me guys. I think I've got all my sign conventions right, and none of the incorrect answers I've tried have said, "check your signs." I've tried the s'=15cm for the image distance (which I used to calculate s in part one, which was correct...) but that didn't work, i.e. -(15/1.1)(25/2.8). I also tried using s'=15-2.8=12.2, putting the image from the objective projected onto the focal point of the eyepiece.

Linus Pauling
Feb12-10, 08:08 PM
P: 190
The answer is in the back of the book, but with different numerical values. I worked out how to get the correct answer for the book numbers, then applied the exact same logic to the question with the values I am asking about... and it says it's wrong...

Register to reply

Related Discussions
Lens' and Magnification Introductory Physics Homework 2
A Few Question On Lens and Magnification Introductory Physics Homework 0
How i can find the magnification of a lens? General Physics 6
Lens Magnification..HELP Introductory Physics Homework 1
Lens magnification problem Advanced Physics Homework 21