The LED used
Control box with built-in photodetector
Light passing through a water filled tube
Learnt how to measure the speed of light
Practiced using an oscilloscope to measure phase shifts
Understood Lissajous figures
Demonstrated directly that light travels more slowly through water than air
Investigated the relationship between the refractive index and the speed of light in transparent media
This experiment measures one of the most important and fundamental constants in physics - the speed of light. You will measure it in air and in water and experimentally verify that the speed of light slows in transparent media. You will measure the ratio of the speed of light in a vacuum to that in a medium and thereby determine the index of refraction.
Fig. 1: Red light from an LED is modulated with a 60MHz signal and passed through a tube of water onto a photo-detector.
The script for this experiment can be found in the lab script book or on DUO.