- #1
xinlan
- 61
- 0
Homework Statement
On one of the shelves in your physics lab is displayed an antique telescope. A sign underneath the instrument says that the telescope has a magnification of 20 and consists of two converging lenses, the objective and the eyepiece, fixed at either end of a tube 60.0 cm long. Assuming that this telescope would allow an observer to view a lunar crater in focus with a completely relaxed eye, what is the focal length Fe of the eyepiece?
Homework Equations
Length (L) = Fo+Fe
Which Fo = Focal length of the objective lens
Fe = Focal length of the eyepiece
M = -Fo/Fe
The Attempt at a Solution
L = Fo+Fe
60 = Fo+Fe
Fe = 60-Fo
M = -Fo/Fe
20 = -(60-Fe) / Fe
Which Fe would be -3.16
But I got wrong..
Please help me..
thank you..