Annual Conference CLEAPSS Physics investigations
Please ask if you are unsure or need help
DETERMINING THE SPEED OF LIGHT WITH A
MICROWAVE
Evenly spread marshmallows on a plate, and remove the rotating platter from the
microwave. Heat the marshmallow for no longer than 30 seconds, and carefully remove
the plate. There will be areas where more heating has taken place. Measure the mean
distance between 3 of these ‘hotspots’ and this will correspond to half a wavelength.
The frequency is obtained from the reverse label on the reverse of the microwave.
Using the wave equation, we can determine the speed of
light
Speed of E.M radiation (light) = frequency x wavelength
JN, Jan 2014
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