In Bessel's method for measuring the focal length ƒ of a positive lens, a small object and a white screen are set at a fixed separation L, where L > 4f. The lens is moved along a line through the object perpendicular to the screen, and it is found that there are two lens positions where a sharply focused image is produced on the screen, one magnified and one demagnified. The separation between these two lens positions is then measured as distance D. Prove that the lens focal length is given by L² - D² f 4L

Physics for Scientists and Engineers: Foundations and Connections
1st Edition
ISBN:9781133939146
Author:Katz, Debora M.
Publisher:Katz, Debora M.
Chapter38: Refraction And Images Formed By Refraction
Section: Chapter Questions
Problem 126PQ
icon
Related questions
Question
In Bessel's method for measuring the focal length ƒ of a positive lens, a small object and
a white screen are set at a fixed separation L, where L > 4f. The lens is moved along a
line through the object perpendicular to the screen, and it is found that there are two lens
positions where a sharply focused image is produced on the screen, one magnified and
one demagnified. The separation between these two lens positions is then measured as
distance D.
Prove that the lens focal length is given by
L² - D²
f
4L
Transcribed Image Text:In Bessel's method for measuring the focal length ƒ of a positive lens, a small object and a white screen are set at a fixed separation L, where L > 4f. The lens is moved along a line through the object perpendicular to the screen, and it is found that there are two lens positions where a sharply focused image is produced on the screen, one magnified and one demagnified. The separation between these two lens positions is then measured as distance D. Prove that the lens focal length is given by L² - D² f 4L
Expert Solution
steps

Step by step

Solved in 2 steps with 3 images

Blurred answer
Similar questions
  • SEE MORE QUESTIONS
Recommended textbooks for you
Physics for Scientists and Engineers: Foundations…
Physics for Scientists and Engineers: Foundations…
Physics
ISBN:
9781133939146
Author:
Katz, Debora M.
Publisher:
Cengage Learning
University Physics Volume 3
University Physics Volume 3
Physics
ISBN:
9781938168185
Author:
William Moebs, Jeff Sanny
Publisher:
OpenStax
Principles of Physics: A Calculus-Based Text
Principles of Physics: A Calculus-Based Text
Physics
ISBN:
9781133104261
Author:
Raymond A. Serway, John W. Jewett
Publisher:
Cengage Learning
An Introduction to Physical Science
An Introduction to Physical Science
Physics
ISBN:
9781305079137
Author:
James Shipman, Jerry D. Wilson, Charles A. Higgins, Omar Torres
Publisher:
Cengage Learning
Inquiry into Physics
Inquiry into Physics
Physics
ISBN:
9781337515863
Author:
Ostdiek
Publisher:
Cengage
College Physics
College Physics
Physics
ISBN:
9781938168000
Author:
Paul Peter Urone, Roger Hinrichs
Publisher:
OpenStax College