Projects: UDL : UDL Electricity String model of circuit (3-4)
This page last changed on Oct 03, 2007 by ehazzard.
How does electricity move?
Build a model of how electrical charges travel in a circuit and move energy from one place to another.
You can model this process with a circle of students. Form a circle with everyone linking arms, including the teacher. Pretend that the teacher is the battery and a student across the circle is the light bulb.
Let the teacher give a little pull. This is like what a battery does. Right away, every other person feels the pull. The pull goes right around the circle.
Let the person who is the light bulb try to not move. They will feel pushed on one side and pulled on the other. The effort that they must make to try not to move is like the energy the light gets from the battery that makes it heat up.
Now build a similar model of a circuit using string and straws.
Make a necklace of four bendable straws on a piece of string.
Tie the string into a loop, leaving about 20 cm of string that is not inside the straws.
Tape the necklace to a piece of cardboard in a rough rectangle. Leave the string a little loose. Leave two areas where the string is not inside the straws.
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Put a dot on the the string about every centimeter. These represent electric charges that can move inside the wire.
Pull the string to make it go around the loop. This is what a battery does. It forces the electric charges along the wire. Draw in a picture of the battery on a piece of paper and stick it to the cardboard.
Have one person press down lightly on the string and another person pull the string in another place to make it go around. What happens?
Draw a picture of a light bulb and stick in on the cardboard where the person is pressing on the string.
This model is like an electric circuit in some ways. Here is a picture of an electric circuit showing electrons moving along the wires. Of course real electrons are very, very, very small. We can't see them.
What if you cut the string? Could you move charges around the loop?
Cutting the string is like opening a switch. Draw in a picture of a switch somewhere along the wire.
This model is like an electric circuit in some ways. It is meant to be an analogy. Here is a comparison between your string circuit and a real electric circuit.
Here are some ways this analogy is not correct!
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