Polytechnic University of Valencia Congress, INNODOCT 2019

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Measuring the Speed of Light in Water Using a CD
Peter Horváth, Jarier Wannous

Last modified: 10-04-2020


The paper describes a simple method of measuring the speed of light in water using the wave properties of light. The tools used are a compact disk (CD), an aquarium, a laser pointer and a ruler. The key tool is a CD of which the reflective layer has been scratched off. Using the comparison method, we compare the speed of light in water with the already known speed of light in air. The measurement itself will be realized using a ruler and a graph paper. Other than measuring the speed of light in water, the activities offers an experimental proof that during light refraction the wavelength of the light changes while the frequency remains constant, which is an important but not trivial fact about refraction.


Speed of light, simple experiment, wave properties, frequency, wavelength

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