Measuring Speed of Light - Foucault's Method

This section describes the method used by Léon Foucault to measure the speed of light using using a rotating mirror and a fixed mirror.

In 1857, the French physicist Léon Foucault enhanced Fizeau method to measure the speed of light using a rotating mirror and a fixed mirror, as illustrated in the picture below.

Foucault's measurement is based on the following idea:

Using this idea, Foucault was able to measure the speed of light as 299,796,000 m/s. This is very close to today's definition of the speed of light: 299,792,458 m/s.

Speed of Light Measurement by Léon Foucault (csic.es)
Speed of Light Measurement by Léon Foucault

Last update: 2014.

Table of Contents

 About This Book

 Introduction of Space

 Introducion of Frame of Reference

 Introducion of Time

Introduction of Speed

 What Is Speed?

 List of Various Speeds

 Different Speeds Observed in Different Frames

 Measuring Speed of Light - Roemer's Method

 Measuring Speed of Light - Fizeau's Method

Measuring Speed of Light - Foucault's Method

 Newton's Laws of Motion

 Introduction of Special Relativity

 Time Dilation in Special Relativity

 Length Contraction in Special Relativity

 The Relativity of Simultaneity

 Introduction of Spacetime

 Minkowski Spacetime and Diagrams

 References

 PDF Printing Version