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Step |
Instruction |
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1 |
Right a grant /
get funding to purchase some of these low cost plug in the wall style power
meters. They are about $15.00 each. Click
here for purchase
information. |
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2 |
Go over the following with your students:
- Safety instructions provided in the owner's manual / instructions that
come with the power meter
- The basic formula for power which is Volts x Amps = Watts
- Instruct the students on how to use the different display modes
described in documentation that came with the power meter
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3 |
Get a 25 Watt bulb from the store. Also get a bulb to
plug adapter to use.
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4 |
Now you use an AC power meter to measure the AC voltage coming out of the wall.
It should be some where around 120 Volts AC. NOTE: You are responsible for
reading the volt meter manual safety precautions!! But in short, you
verify that your AC volt meter has an AC voltage range able to accommodate 120
Volts AC, set the voltage meter to AC voltage (MAKE SURE It's not set to
AMPS), and stick the probes into the wall outlet. It's easy. Just
don't touch the metal parts of the probes. |
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5 |
Now that you have measured the exact voltage level of your class room outlet,
tell the students to right down this as a constant to use in their formula for
power. |
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6 |
Have the students right down how many Amps the 25 Watt Bulb is drawing on
their work sheet. NOTE: If you use more than 25 Watts, you run the risk of
some one touching the bulb and getting burnt!! |
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7 |
Now have them multiply the voltage you measured from the outlet, times the
current measured by the power meter, and calculate how much difference there is
between the power indicated by the power meter and what was calculated by using
the formula. |
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8 |
Wrap up with a discussion with having different lab / student teams report out
on what they observed. |
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