Unit 52 Laboratory Activity: Microwave measurements
Goal: To determine the length of an electromagnetic wave
This lab is based on Dave Ansell's Measuring the speed of light experiment.
- Easily meltable food (bar chocolate, chocolate chips, butter, or marshmallows)
- Flat tray that can be used in a microwave
- Centimeter Ruler
- Spread the food evenly on the tray.
- Remove the "carousel" or other rotation device from the microwave.
- Set the tray with the food on the floor of the microwave.
- Run the microwave for 10-30 seconds, until melting spots appear on different places on the food. Do not melt the food entirely.
- Measure the distance between melting spots. This distance is the distance between "troughs" of the wave and is equal to 1/2 the total wavelength.
- Check the specifications for your microwave. These should list the frequency of the wave (usually around 100Hz).
- Describe your setup and procedure.
- Convert your measurements to meters (1cm = 1/100 meter).
- Determine the average wavelength from your measurements. First, determine the average distance between spots, then multiply this distance by 2.
- Calculate the speed of light as c = λ * ν where λ is the wavelength you measured and ν is the frequency of your microwave.
- The actual speed of light is around 2.99 * 108meters/second. How accurate was your measurement?
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