Microwaves Labs

Lab One: Microwaves are Waves

Food can cook unevenly in the microwave, because of high and low points in the intensity of the microwave radiation .As the waves bounce back and forth in the box, constructive and destructive interference takes place.

1) Take a piece of 1” thick Styrofoam and cut it to the same size ( or slightly smaller) than the microwave bottom

2) Obtain a paper towel and soak it in 15mL of water. Cover the Styrofoam with the wet paper towel.

3) Put a piece of thermal fax paper over this and place the combination inside the microwave oven.

4) Cook for about 15 seconds

5) Repeat this experiment twice more.

6) Repeat the experiment three more times, suing a paper towel soaked in 30 mL of water.

Analysis:

1) Trace the black pattern that you see on the fax paper. Describe the pattern.

2) Explain why the pattern has the shape it does.

3) Does the pattern change when the amount of water changes? Why or why not?

4) Repeat the experiment using a chocolate bar. You may have to play around with the cook time settings to see a pattern. What type of wave pattern do you notice on the chocolate bar? Why?

5) Would the results for this lab changes if you places a shiny object on top of the fax paper? Why or why not?

Lab Two: Creating a Grape Plasma

1) Take a thin skinned grape and cut it in half, but not all the way. Leave a small bridge of skin connecting the two halves.

2) Dab the excess juice from the grape and place the whole thing like an open book in the microwave oven.

3) Cook for 10 seconds.

Analysis:

1) What happens to the grape after 10 seconds?

2) Explain how the skin flap acts like a conductor.

3) What happens to the resistance of the grape as it heats up?

4) Repeat the experiment using the “hot spots” you found in lab one. Does the grape behave differently in the hot spots vs. the cold spots?

Lab Three: CD Burning

1) Use a CD you no longer want.

2) Place the CD in the microwave , label side down, propped up from the floor, using old plastic film containers.

3) Turn off the room lights

4) Turn the microwave oven on for 5 seconds and record your observations.

5) Turn off microwave before the room fills with gases given from the almost burnt CD.

6) Repeat the experiment with the label side up.

Analysis:

1) Does the CD have a random or ordered pattern etched into it?

2) CD’s are made of aluminum. Explain this element’s role in this experiment.

Lab Four: No match for the match

1) Place a wooden tooth pick ( or match) on a cork so it is standing up in the microwave.

2) Light the top so it burns slowly.

3) Turn the over on for 10 seconds. Record your results.

Analysis:

1) Explain why the toothpick behaved as it did.

2) Repeat this experiment using a burning candle. What state of matter did you create?