Measure the speed of light with marshmallows.  Fill a dish with a layer of marshmallows. Place the plate in a microwave oven so that it remains stationary.  I removed the glass tray and placed an inverted bowl over the rotor mechanism. The plate of marshmallows is placed on the inverted bowl.  Heating on the order of 30 seconds was sufficient to see some marshmallows swell due to local heating.  Remove the plate and measure the distance between rows of swollen marshmallows. I estimated between 5 – 6 cm.  The frequency of the microwaves is given on the back of the microwave (2450 MHz).  The speed of microwaves is the product of the wavelength and the frequency.

C = (2450 MHz)(10 cm) = 2.45 x 108 m/s       

C = (2450 MHz)(12 cm) = 2.94 x 108 m/s

Speed of Light