This one didn't make a lot of sense to me, but anything that can get a kid that young to try to explain lambda to us has to be worth a vote. I'd love to see more in that age range curious and involved.

*homeschooler

*cuecards

The principle is sound, but something doesn't make sense to me. The speed of light is: 1.18028527 × 10^10 inches per second. At 2.45 GHz, this yields a wavelength of 4.82 inches. There should be two hot spots per wavelength so why does she measures about 4.5 inches between each hotspot. Shouldn't they be spaced at 2.41 inches apart?

i have a niece that age. all she's concerned with is "kitties" and puppies and typical little girl stuff. the thought of my niece trying to explain waves is just hysterical to me.

You are technically measuring the standing waves set up by the magnetron.

You can play around with online microwave: http://www.colorado.edu/physics/2000/microwaves/mwintro.html

So that is why the peaks of the standing waves are ONE LAMBDA not LAMBDA/2. Anyways, I believe many microwaves have discs that spin in front of the horn antenna in addition to rotating plate.

Technically the correct lesson is:
c(measured) = lambda * freq
c(measured) = (4.5in * 2.54cm/in * 1m/100cm) * 2.45E9 cycles/second = 2.8E8 m/s
which is pretty close to theoretical 3.0E8m/s for speed of light.

Joedirt,

Thanks for the link. From this page:
http://www.colorado.edu/physics/2000/microwaves/hotspots.html

It shows the hotspots generated from standing waves. My question is, shouldn't water molecules align to the positive peaks as well as the negative peaks? If yes, then there should be hotspots at LAMBDA/2 also.

Note that the chocolate bar is placed in the microwave at a diagonal. If the standing wave pattern is generated with front-to-back and right-to-left waves, then she measured peaks at a diagonal which would yield at an answer that is 1.4 times larger.

Eat a lot of decent Beligan, Swiss, or German Chocolate.. then go to the toilet. Don't flush! You will then have Hershey's Chocolate. Form into bars. Enjoy.

So the speed of light is 4 inches? I thought it was 299,792,458 meters per second.