Register to reply

Optics Q; Bessel's method

by Perses
Tags: bessel, method, optics
Share this thread:
Oct1-05, 11:13 PM
P: 14
I'm having a bit of trouble finding a place to start in one of my optics questions. I have to find Bessel's method for focal length of a lens. Any pointers on where to begin or a general direction, that would be greatly appreciated! Here's the question:

A thin lens is moved along the optical axis between a fixed object and a fixed image screen. The object and image positions are separated by a distance L that is more than four times the focal length of the lens. Two positions of the lens are found for which an image is in focus on the screen, magnified in one case and reduced in the other. If the two lens positions differ by distance D, show that the focal length of the lens is given by;

f = (L^2 - D^2)/4L.
Phys.Org News Partner Science news on
Wearable 4MM jetpack tested on speed, agility for runners (w/ Video)
How did evolution optimize circadian clocks?
Corn spots: Study finds important genes in defense response
Oct2-05, 07:13 PM
P: 14
any help anyone could offer would be appreciated, thnx

Register to reply

Related Discussions
Bessel's Equation Solution Proof Differential Equations 16
Differential equation reducible to Bessel's Equation Differential Equations 9
Bessel's Eq. of order 0 and solution help Calculus & Beyond Homework 5
S.E in cylinder - Bessel's equation Introductory Physics Homework 5
Washer method and disc method for finding volumes of graphs Calculus 5