|
||||||||||||||||||||||||||||||||||||||
Stored Energy Home Experiment
This is a simple experiment that illustrates power converting to heat energy and thermal energy loss. The loss of energy measured in this experiment can be related to energy loss in a plasma experiment.Materials:
- A microwave oven (a bunson burner and beaker may work)
- Two identical microwave-safe mugs
- A cooking pan, say 9"x9", or a cooking skillet
- Water at or near room temperature
- A thermometer accurate to within 1 or 2 degrees to measure the water temperature
- OPTIONAL: Graph paper or a graphing computer program (EXCEL works well).
Hypothesize First
- Guess how hot 2 cups of water will get from 2 minutes in a microwave.
- (for extra credit)
Calculate
how hot 2 cups of water will get from 2 minutes in a microwave.
- Guess how the hot water in a cup and in a pan will cool in 10, 20 and 30 minutes. (Will the plot of temperature decrease be a straight line?)
- What could invalidate the calculations for this experiment?
Make sure you know how to operate a microwave oven SAFELY!
STEPS
- Put 8 ounces of cold tap water in each of two identical mugs.
- Measure the temperature and record it.
- Place each cup side by side in a microwave (place each cup the same distance from the center of the microwave for equal heating).
- Heat for 2 minutes.
- Measure the temperature and record it.
- Pour the water from one cup into a cooking pan or skillet.
- Every 5 or 10 minutes, measure and record the time and temperature (you may have to pour the water from the pan back into the cup for measuring).
- Continue measuring for 30 to 60 minutes.
- Plot the results on a graph with seconds along the horizontal axis and temperature along the vertical axis.
Variations
- If you moved water from the pan to a cup for measuring the temperature, repeat the experiment but leave the water in the pan for a full 30 minutes (i.e., don't it pour back and forth) and see if the results change.
- Perform the experiment with a different type of thermometer.
Analyze
- How do the results differ from what you expected?
- How much energy was injected into the water by the microwave?
- What is the power of the energy loss from the water during the first few minutes of cooling?
- What are the "forms of energy" flow in this experiment?
Related Pages
- There's no substitute for doing this yourself, but if you must peek, here are some results.
- Home Experiment Calculations!
- Now test yourself with Tea Time.
home - about fusion - interactive physics - ask a physicist - virtual tokamak