Posted by
investment
557 days ago
(http://www.mrhood.co.uk)
Category: Science Discovery Environment |
Microwaves
So, we can find out the wavelength of the microwaves by measuring the distance between the hot spots, and multiplying by 2. OK, first I took out the little mechanical thingy that turns the food around inside the oven. We don’t want the food evenly heated, we want to get the hotspots in one place so we can see where they are to measure them.
Turntable
The Milky Way didn’t work out too well, and the marshmallows weren’t a lot better….
Milky WayMarshmallow
… but egg white works quite well. It took about 30 seconds on full power to get visible results I could measure:
Egg white works quite well
So, the hot spots are 61mm apart, so the wavelength of the microwaves inside the oven is 122mm. If I look at the back of my microwave oven, I can find the plate that tells me the frequency of the radiation:
Rating plate
It’s 2 450 MHz, or 2 450 000 000 waves per second.
Now I can figure out the speed of light. Light is just electromagnetic radiation, same as my microwaves. They all travel at the same speed, and that can be calculated by the formula /cgi-bin/mimetex.cgi?\reverse~v~=~f\lambda, or the frequency times the wavelength. So, the speed of light, as established in my kitchen this afternoon, is v = 2 450 000 000 x 0.122 = 298 900 000 metres per second. Google reckons it’s 299 792 458 m / s, so my results are about 0.3% off.
Not bad for a Saturday afternoon.
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