How do we keep from overheating the wires in an electrical circuit?
Electrical Resistance is when something causes electrons to slow down due to friction. Some parts of a circuit have more resistance than others. An incandescent light bulb increases resistance through the filament. This thin, long wire creates more resistance, heating up and converting heat energy into light energy. If a part of a circuit heats up more than it should, it could cause an electrical fire.
Resistance cannot be directly measured in our classroom. Instead, we can measure the voltage and current, and calculate the resistance according to Ohm’s Law. The equation is
Resistance (  ) = Voltage (V) ÷ Current (Amp)
1.
Observe the car fuse at the front of the room. State any characteristics you think that might be important for a fuse to have:
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2.
Use the power source at the front of the classroom.
3.
Create the circuit with a foil fuse. The fuse must be very, very thin
Power Source (notice there is NO light)
4.
Turn the switch on. The fuse will “blow”. Turn the power back OFF.
5.
Add a Christmas light to the circuit after the switch. Put a new (unblown) foil fuse into place.
6.
Close the switch. Observe if the fuse blows.
7.
If the circuit is still in tact, short out the light by creating a short circuit
(putting a wire directly from one side of the light bulb to the other side).
Record what happens below:

1.
Define resistance:
2.
Why would a car have a fuse?
3.
Explain why the foil fuse burns out using the terms current, heat, and resistance.
4.
Why do houses have fuses or circuit breakers?
5.
Determine if your home has a fuse box, or if it has circuit breakers. Have your guardian show you the electric box in your house and get this paper signed
I showed my son/daughter the fuse box/circuit breaker (circle one) in our house.
Guardian Signature