Chapter 2, Problem 75A

To determine

The way speed of light was determined. The way, experimental techniques improved the way to make results more accurate.

Explanation of Solution

Introduction:

The speed of light in vacuum is $3\times {10}^8\text{m/s}$ . An object cannot have speed greater than speed of light. Before the correct measurement of speed of light, it was assumed that it is very fast or infinite that it cannot be measured.

Ole Roemer was a Danish astronomer who first determined the speed of light in1676. He measured it by noting the time of eclipse of Jupiter’s moon Io. With improvement in technique, the speed of light is accurately measured to: $2.99792\times {10}^8\text{m/s}$

Foucault method is used to measure the speed of light. This method uses a beam of light to reflect from a rotating mirror towards a fixed mirror. This creates two reflected beams. The angular displacement and time for the beam to travel are related and can be used to measure the speed of light.