Measure the Speed of Light with a Chocolate Bar

All waves in the electromagnetic spectrum (light, x-rays, radio waves, microwaves, etc.) travel at the speed of light c=299,792,458 m/s. For any wave, the wavelength times the frequency yields the speed:

λν = c

Microwave ovens operate by creating a standing wave inside of them. Different parts of the wave cook better than other parts - imagine a three dimensional grid of evenly spaced dots where the cooking is best. The distance between these dots is the wavelength λ. Our microwave operates at a frequency of ν=2.45 GHz as most conventional ones do, so this yields a wavelength of

λ = c/ν = .122m or about 4.8 inches.

Of course, the spinning tray in the microwave is put there to offset the uneven cooking. Removing this tray, you can measure the speed of light by cooking a bar of chocolate for about a minute and half. If your bar of chocolate is big enough, there will be two circular areas where the chocolate has melted and the distance between their centers is about 4 inches. Multiplying that by the known frequency ν of the microwaves yields the speed of light!

http://wogsland.org/bradley

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[Claudio Drews]

If that little girl were like me, that chocolate bar would have disappeared faster than the speed of light. I also think it is wrong to put a perfectly good chocolate bar in the microwave oven.

[NickandFriendsCo]

its hermonine

[katddem3]

this girl makes me feel worse about my general lack of physics understanding

[James Rogers]

this young girl is a genius, i think she will grow up to be a physicist just like me :D

[Simon Rose]

my, all that precociousness and she pops the plate in the microwave without centering it, oh my mild adult OCD-ness hurts me.

[turkmko]

Liking your comment. You almost did it to top comments

[Masterazza25]

Measured by how quickly a fat person eats it!

[Mr Zaphraud]

Actually, the truth is if the speed of light were any different, you'd get the same results. Reason: the magnetron itself uses the lightspeed limitation on the speed of electrons to generate the microwaves in the first place! So, if lightspeed were different, the frequency of the microwave would be different, and (if the magnetron still worked) you'd get similarly distanced spots as well.

Still, awesome science. Would have been 100% solid if the 2.45 were from solid state, etc..

[bk9001]

You were good dear young scientist. I also applaud parents' efforts to involve a young child in a scientific experiment but in a way that is very age appropriate. Great job!

[dontwantnochannel]

Please... teach your kid to use metric units.

[aws316]

Fake

[Harrison McClure]

if were that little girl i wouldve thrown that discusting hershey bar in the bin