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The current generated when one copper coil swings through a magnetic field will start a second coil swinging, showing some of the ways that electricity and magnetism interact.
Note: This Snack may be difficult to build properly or may not clearly show the desired results even if it is built correctly. This may be due to the effects being very subtle and/or hard to observe. The construction technique may require exceptionally fine tuning and tinkering, or it may just be inherently difficult to execute properly. That being said, if you're up for a challenge, go for it!
Pull one coil back and then let it swing back and forth over a magnet. Notice that the second coil begins to swing.
Change the polarity of the magnet by flipping it 180° and reinserting it into the 2 x 4. Swing the pendulum again and notice what happens.
Remove the tape at the top of one of the coils, and reverse the coil. Retape the leads. Swing the pendulum again and notice what happens.
Connect a clip lead from one place where the copper leads are twisted together to the other. Swing a coil and watch what happens.
When you start the first coil swinging on and off the end of the first magnet, a current is induced in the coil. Since the two coils are part of the same continuous circuit, this current also flows through the second coil.
A current-carrying coil of wire behaves like a magnet. The magnetic field around the second magnet attracts or repels the second coil, setting the second coil in motion. (Alternatively, you could say that the magnet exerts a force on the current flowing through this second coil. However, the electromagnet explanation is simpler.)
When the second coil swings, it becomes a generator too—that is, a current is induced in the coil. The resulting current in the two connected loops is a result of both coils swinging through both magnetic fields.
Reversing the coil or the magnet's polarity changes the direction of current induced in the coil. This in turn changes the direction in which the other coil swings.
The clip lead short-circuits the coils. The electric current generated by the coil you are swinging will not flow through the second coil, so the second coil will not move.
You can monitor the current in the circuit by placing an ammeter (100 microamperes) in series in the circuit. You can also monitor the voltage in the circuit by placing a voltmeter (1 volt) in parallel in the circuit: Clip it to the two twisted wire junctions. Try to observe the phase relation between the swinging coils and the voltage and current measured by the meters.
Two pendulums influence each other’s motion to create Intriguing patterns.
The attraction and repulsion of magnets produces entrancing, unpredictable motion.
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Attribution: Exploratorium Teacher Institute