DIY speed of light measurement

Next time you are out having a beer and your short of a few bob, here is a sure fire way to win a bet with your friends. You can tell them that you can prove the speed of light is 300000000 meters/second using just a chocolate bar and a few household items to a good degree of accuracy.

You will need

• A large chocolate bar
• A microwave oven
• A ruler

Heres how.

First remove the stirring plate from the microwave and place the chocolate bar inside. With the plate removed, and the bar ready turn the microwave on until u see the chocolate bar begin to melt in places. Removing the stirring plate causes "standing waves" accross the oven and at the peak of these waves will be "hot spots". These hotspots should be visible on the chocolate as this area will melt first. Since these standing waves are electromagnetic radiation they travel at the speed of light and the distance between two hotspots on the chocolate coincides with the wavelength.

Measure the distance beween the hotspots with the ruler and make a note of it, make sure to use the cm or mm scale and make the conversion to meters. Using a simple formula we can now prove that the waves propagate at 300000000m/s. The frequency of a wave is related to the wave length and speed by,

speed/frequency=wavelength

or

Speed (0f light)=Wavelength*frequency

We now know the wavelength but we need to know the frequency, this can be found either in the manual for the microwave of on the back plate of the microwave.

You now have all the information to prove that light travels at 344 miles/second and win a ton of bar bets.