East is looking for the region's kitchen sink scientists to measure the
speed of light with just a microwave, some bread, margarine and a ruler.
If you are
under 16 years of age, please ask an adult to help you with this experiment.
Experiment to calculate the speed of light in your kitchen
Audio and Video links on this page require Realplayer
A microwave-proof plate
A bowl (to cover microwave turntable mechanism)
An oven glove or tea-towel
Four slices of bread
A tub of margarine
all, arrange four slices of bread on a plate - putting them as close together
as you can. Imagine you've created one giant slice of bread from the four
with his microwave
the slices with really, really thick margarine - making sure to spread
over the joins between the slices. When finished it will look like one
giant slab of margarine.
turntable out of the microwave and cover the turning mechanism with a
shallow bowl or plate.
create waves that have hot and cold spots.
the turntable is there to get rid of those spots to ensure an even cooking
process, but for this experiment we want to use those hot and cold areas.
taken out the turntable and covered the mechanism, place your plate of
bread and margarine in the microwave and cook it for a maximum of 20 seconds.
for melted spots to start appearing in the margarine. As
soon as this starts to happen, turn off the microwave.
oven glove (or tea towel) to protect your fingers from any heat coming
off the plate, carefully take out it out of the microwave and place it
on the kitchen worktop or table (making sure it's a suitable place to
put a slightly warm plate).
are the clue
should have some melted spots in it as the microwave creates a series
of energy waves which run back and forth across the oven and its contents.
wave is at a peak or trough, these are the hottest spots, or where the
energy is at its greatest.
points, the food is cooked - or in this case it's the spots where the
margarine has melted.
This is created
by a single wavelength.
Speed of light
Just type in the
distance between the melted bits of margarine, and the frequency off the back
of your microwave (sometimes it's inside the door) to calculate the speed of
light in your kitchen.
send your data to the Naked Scientists
website. This is an external website not part of the BBC
The BBC is not responsible for the content of external internet sites
If we now
measure the horizontal distance between two melted areas (it can be on
the bottom or top of the slice of bread) this is half a wavelength.
this measurement, it's what you'll need to allow our computer to calculate
the speed of light.
need a number from the sticker on the back of your microwave.
You are looking
for the frequency - either in mega or gigahertz - which is the number
of waves your microwave makes every second. Do
not confuse this with the power rating, which is measured in Watts (650W,
the speed of light multiply how big the waves are (the measurement you've
just taken between the melted areas) by how many waves there are per second
(the frequency number from the back of your microwave).
numbers into this calculator (selecting the unit of measurement you've
used and the frequency output of your microwave) and press convert.
Now you have
how fast the speed of light is according to your kitchen.
calculator has given you a figure, you can continue to submit your findings
to The Naked Scientist website to be included in their Hall Of Fame.
is your measurement to the speed of light? Find out by visiting The
Naked Scientists' website. Where you can also see how other people
got on with this experiment.
The BBC is not responsible for the content
of external websites
wondering what to do with the bread, here
are some recipe ideas from BBC Food.