I was looking for some info on filter colour/wavelength (at a price I can justify!) and I found something produced by an education trust
on teaching Y5 science.
The following I found very interesting -
Measuring the Speed of Light
On SCOPE's Light episode, Talia uses cheese and a microwave to measure the speed of light in a kitchen.
Here's how she did it. Watch the clip.
What you need
· cheese slices
What to do
1. Start by covering the plate evenly with slices of cheese.
2. Before you put the plate in the microwave remove the turntable so it doesn't rotate when the microwave oven is
3. Put in the plate of cheese and microwave until the first signs of cheese melting (10 seconds usually).
4. Take the cheese plate out and examine it. There should be several hot spots over the cheese where there has
been melting, whilst the rest will be still cold and solid.
5. Use the ruler to measure the shortest distance between hot spots. Do a few. The distance should be about the
6. This distance is half the wavelength of a microwave, so to get full wavelength, double your number.
7. Next find the frequency of the microwave. It should be written on it somewhere. Most are 2450 Megahertz, or
2450 million Hertz.
8. Almost there. Now just multiply the frequency by the wavelength and you have the speed of microwaves (which is
the same as light).
Here is an example:
6 cm between spots, means a 12 cm wavelength. Or 0.12 metres.
So 0.12 * 2,450, 000, 000 Hz = 294, 000,000 m/s or about 1 billion km/hr