In this video you see my son Tom and I conducting a simple, yet important experiment, that allows you to approximate the speed of light only using a microwave oven and cheese.  How?  Well the speed of light is equal to the frequency times the wavelength.  And a microwave oven comes with an indication in the back that shows the frequency.  Ours is 2450 MHz.  So then all you need to do is to melt cheese in a plate and with a simple ruler measure the distances between the first two areas in the cheese that start melting.  In order to do this it is important that you prevent the platter of the microwave from turning.  For other details just watch the video.

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Paco on March 6, 2011  · 

It´s a good way to show the nature of the waves (no matter its frecuency) but inside the microwave you don´t have a “pure” wave because the waves are reflecting so in fact you don´t have a pure wavelength equivalent to those 2450 MHz. Anyway, well done very instructive. In Spain are not used to show “practical” demonstrations of the theory. Congrats.

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Fabricio on March 6, 2011  · 

Good example. I think the 17 % error has to do with the fact that at higher frequencies things tend to get harder to measure in physical tests. If the frequency example would have been at lower frequency (in HZ) I think it would have been colser to the measurment of the speed of light we all know

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Francesco Cardi on March 7, 2011  · 

Back to physics, nice!

But, reinforcing what Paco rightly observes (“no pure wave”, reflection effects):

1) in the experiment you assume that radiation wavelenght equals “first two areas in the cheese that start melting”. Why the two things should be the same? They have nothing to do with each other, I understand.

2) also, the radiation is emitted from how many points, just one?

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Haim on March 8, 2011  · 

A better experimental setup: use “light” cheese

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Sebastian Wain on March 9, 2011  · 

I remember now measuring the sound speed calculating the time between the emision of a sound with its reception.

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Daniel on March 13, 2011  · 

¿Que dice Tom en 3:05? “… everything from radio to (…)”

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Barry @ halogen ovens on April 1, 2011  · 

I love little experiments like this, really cool!

Off topic: Nice house!

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