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Measuring the speed of light in your kitchen

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jgh29447
40878.  Tue Dec 20, 2005 12:35 pm Reply with quote

You can measure the speed of light in the average kitchen.
Line a microwave proof dish with a single layer of tightly packed marshmallows. Zap this in the microwave on low power for about 1 minute (dont use the turntable). You will see a regular series of scorch marks on the surface, so measure repeatedly the distances between adjacent scorch marks & calculate the average distance - this is half the wavelength of the microwaves. Then look at the rating plate on the back of the oven - it will have something like 2450 Mz printed on it. (Thats the frequency).

So now if you multiply the wavelength by the frequency you get the speed.
ie 2,450,000,000 Hz * 0.122 Metres = 2.99 x 10 to the power of 8

This is within 5% & about the same figure Einstein was working with.
What he would have given for a microwave oven huh?

Does anyone have any other domestic science experiments ?

 
QI Individual
40929.  Tue Dec 20, 2005 3:27 pm Reply with quote

jgh29447 wrote:
Line a microwave proof dish with a single layer of tightly packed marshmallows. Zap this in the microwave on low power for about 1 minute


A tightly packed layer of marshmallows heated for 1 whole minute will give you a very messy microwave oven. If you haven't nuked marshmallows before try one for a few seconds. Fascinating to see to which size these things balloon in a few seconds. Result is a nice warm gooey marshmallow. Quite edible.

 
JumpingJack
40975.  Tue Dec 20, 2005 5:54 pm Reply with quote

Gee, that's fascinating.

 
Scalpy
40982.  Tue Dec 20, 2005 6:28 pm Reply with quote

I remember trying that once when I was younger, my key mistake came when I left a spoon in with the marshmallows, it arced and set them microwave on fire....

 
Stressed parent
40993.  Tue Dec 20, 2005 7:57 pm Reply with quote

Quote:
Does anyone have any other domestic science experiments


The ones my kids love are:

baking powder and vinegar

liver and hydrogen peroxide

dissolving a raw egg's shell in vinegar and seeing how hard you have to bounce it before it breaks (mum then having to clean up subsequent mess)

there are some more at :

scifun.chem.wisc.edu/homeexpts/homeexpts.html

 
Tas
41024.  Wed Dec 21, 2005 4:20 am Reply with quote

Quote:
Gee, that's fascinating.


I thought it was QI, personally!

:-)

Tas

 
Corelina
41086.  Wed Dec 21, 2005 9:18 am Reply with quote

Well, as we have learned in Braniac yesterday it is quite dangerous to heat up your microwavable Christmas Pud, doused in Brandy if you leave some foil and a spoon on the dish by accident in a microwave.

DO NOT TRY THIS AT HOME

 
tetsabb
41151.  Wed Dec 21, 2005 12:23 pm Reply with quote

Corelina wrote:
Well, as we have learned in Braniac yesterday it is quite dangerous to heat up your microwavable Christmas Pud, doused in Brandy if you leave some foil and a spoon on the dish by accident in a microwave.

DO NOT TRY THIS AT HOME
?

So where can I try it?

 
Rory Gilmore
41157.  Wed Dec 21, 2005 12:33 pm Reply with quote

They did it outside somewhere.

 
wgboy
41377.  Thu Dec 22, 2005 8:59 am Reply with quote

And don't wear nylon clothing in a petrol station

 
Rory Gilmore
41415.  Thu Dec 22, 2005 10:44 am Reply with quote

Or wave a flamethrower around, but I don't think that made the final cut.

 
Caradoc
41702.  Sat Dec 24, 2005 9:42 pm Reply with quote

Once you have taken your microwave oven outside & have constructed a bunker from which you can safely observe the results (H&FS requirements being met) try putting your xmas lights in the microwave oven.

 

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