Measuring the Speed of Light with Fizeau's Wheel Assume Fizeau's wheel has 360 teeth and rotates at 26.3 rev/s when a pulse of light passing through opening A in the figure is blocked by tooth B on its return. If the distance to the mirror is 7,500 m, what is the speed of light? В Toothed Mirror wheel Fizeau's method for measuring the speed of light using a rotating toothed wheel. The light source is considered to be at the location of the wheel; therefore, the distance d is known. SOLUTION Conceptualize Imagine a pulse of light passing through opening A in the figure and reflecting from the mirror. By the time the pulse arrives back at the wheel, tooth B has rotated into the position previously occupied by opening A. Categorize The wheel is a rigid object rotating at constant angular speed. We model the pulse of light as a particle (under constant speed Analyze The wheel has 360 teeth, so it must have 360 openings. Therefore, because the light passes through opening A but is blocked by the tooth immediately adjacent to A, through what angular displacement must the wheel rotate (in rev) during the time interval in which the light pulse makes its round trip? 1 A0 = 360 rev Use oavg to find the time interval for the pulse's round trip (in s): At Δε From the particle under constant speed model, find the speed of the pulse of light (in m/s): 2d m/s Δε Finalize This result is very close to the actual value of the speed of light. EXERCISE Assume in Fizeau's experiment that the mirror is a distance 7,200 m away.
Measuring the Speed of Light with Fizeau's Wheel Assume Fizeau's wheel has 360 teeth and rotates at 26.3 rev/s when a pulse of light passing through opening A in the figure is blocked by tooth B on its return. If the distance to the mirror is 7,500 m, what is the speed of light? В Toothed Mirror wheel Fizeau's method for measuring the speed of light using a rotating toothed wheel. The light source is considered to be at the location of the wheel; therefore, the distance d is known. SOLUTION Conceptualize Imagine a pulse of light passing through opening A in the figure and reflecting from the mirror. By the time the pulse arrives back at the wheel, tooth B has rotated into the position previously occupied by opening A. Categorize The wheel is a rigid object rotating at constant angular speed. We model the pulse of light as a particle (under constant speed Analyze The wheel has 360 teeth, so it must have 360 openings. Therefore, because the light passes through opening A but is blocked by the tooth immediately adjacent to A, through what angular displacement must the wheel rotate (in rev) during the time interval in which the light pulse makes its round trip? 1 A0 = 360 rev Use oavg to find the time interval for the pulse's round trip (in s): At Δε From the particle under constant speed model, find the speed of the pulse of light (in m/s): 2d m/s Δε Finalize This result is very close to the actual value of the speed of light. EXERCISE Assume in Fizeau's experiment that the mirror is a distance 7,200 m away.
College Physics
11th Edition
ISBN:9781305952300
Author:Raymond A. Serway, Chris Vuille
Publisher:Raymond A. Serway, Chris Vuille
Chapter1: Units, Trigonometry. And Vectors
Section: Chapter Questions
Problem 1CQ: Estimate the order of magnitude of the length, in meters, of each of the following; (a) a mouse, (b)...
Related questions
Question
Transcribed Image Text:Measuring the Speed of Light with Fizeau's Wheel
Assume Fizeau's wheel has 360 teeth and rotates at 26.3 rev/s when a pulse of light passing through opening A in the figure is
blocked by tooth B on its return. If the distance to the mirror is 7,500 m, what is the speed of light?
В
Toothed
Mirror
wheel
Fizeau's method for measuring the speed of light using
a rotating toothed wheel. The light source is considered
to be at the location of the wheel; therefore, the
distance d is known.
SOLUTION
Conceptualize Imagine a pulse of light passing through opening A in the figure and reflecting from the mirror. By the time the
pulse arrives back at the wheel, tooth B has rotated into the position previously occupied by opening A.
Categorize The wheel is a rigid object rotating at constant angular speed. We model the pulse of light as a particle
under constant speed
Analyze The wheel has 360 teeth, so it must have 360 openings. Therefore, because the light passes through opening A but is
blocked by the tooth immediately adjacent to A, through what angular displacement must the wheel rotate (in rev) during the
time interval in which the light pulse makes its round trip?
1
A0 =
360
rev
A0
to find the time interval for the pulse's round trip (in s):
At
Use @avg
At =
Δε
From the particle under constant speed model, find the speed of the pulse of light (in m/s):
2d
C =
Δε
m/s
Finalize This result is very close to
the actual value of the speed of light.
EXERCISE
Assume in Fizeau's experiment that the mirror is a distance 7,200 m away.
Hint
(a) What time interval must elapse (in s) between the times when a notch is positioned to allow light through? (Use
c = 3.00 x 108 m/s for the speed of light.)
1
of the time
360
(b) Suppose there are 360 notches equally spaced on the wheel, so that the time calculated in part (a) is
needed for a complete rotation of the wheel. How many rotations per second would the rotating wheel be turning for the
reflected light to pass through?
rotations/s
Need Heln?
Read It
Expert Solution
This question has been solved!
Explore an expertly crafted, step-by-step solution for a thorough understanding of key concepts.
This is a popular solution!
Trending now
This is a popular solution!
Step by step
Solved in 4 steps with 1 images
Knowledge Booster
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, physics and related others by exploring similar questions and additional content below.Recommended textbooks for you
College Physics
Physics
ISBN:
9781305952300
Author:
Raymond A. Serway, Chris Vuille
Publisher:
Cengage Learning
University Physics (14th Edition)
Physics
ISBN:
9780133969290
Author:
Hugh D. Young, Roger A. Freedman
Publisher:
PEARSON
Introduction To Quantum Mechanics
Physics
ISBN:
9781107189638
Author:
Griffiths, David J., Schroeter, Darrell F.
Publisher:
Cambridge University Press
College Physics
Physics
ISBN:
9781305952300
Author:
Raymond A. Serway, Chris Vuille
Publisher:
Cengage Learning
University Physics (14th Edition)
Physics
ISBN:
9780133969290
Author:
Hugh D. Young, Roger A. Freedman
Publisher:
PEARSON
Introduction To Quantum Mechanics
Physics
ISBN:
9781107189638
Author:
Griffiths, David J., Schroeter, Darrell F.
Publisher:
Cambridge University Press
Physics for Scientists and Engineers
Physics
ISBN:
9781337553278
Author:
Raymond A. Serway, John W. Jewett
Publisher:
Cengage Learning
Lecture- Tutorials for Introductory Astronomy
Physics
ISBN:
9780321820464
Author:
Edward E. Prather, Tim P. Slater, Jeff P. Adams, Gina Brissenden
Publisher:
Addison-Wesley
College Physics: A Strategic Approach (4th Editio…
Physics
ISBN:
9780134609034
Author:
Randall D. Knight (Professor Emeritus), Brian Jones, Stuart Field
Publisher:
PEARSON