Measuring the speed of light: results

Answers to questions

Q1. How does this result compare with the speed of light in air?

A1. The value for the speed of light in air is taken to be 3 x 10⁸ m·s^-1

Q2. Investigate the definition of the term Refractive Index and see whether you can calculate an approximate value for the expected speed of light along the fibre optic cable. (The Refractive Index of the polymer used is about 1.6)

A2. Refractive Index is defined as the ratio Speed of light in Air / Speed of light in the medium. In this case we have:
1.6 = 3 x 10⁸/v where v is the speed in the fibre optic cable.
Hence v = 3 x 10⁸ / 1.6 which gives 1.9 x 10⁸ m·s^-1
This is the value calculated from the experiment.

Credits

This experiment was written by the design team at Lascells Ltd.