Students interact with a simulation of a generator that can be toggled between an alternating current and direct current generator.
To introduce the simulation, paraphrase:
Take a look at this simulation of a generator. This simulation shows a simplified view of a generator where the magnet is stationary (i.e. it doesn’t move) and a copper coil rotates through the magnetic field.
Note: Intended answers to suggested questions below are indicated with bullets. Do not read these out to the students: they are available if you need to help your students come up with an answer.
Where’s the magnet?
- The magnet is the u-shaped, red and blue structure.
What do you think represents the conductor loop copper coil? (small, rectangular loop of red)
In generators, conductor loops are often copper coils with hundreds of windings of insulated wire.
What else do you see?
Students may be able to identify parts. If not, you can prompt them to identify them.
What are these blue lines?
- The magnet creates a magnetic field.
What is this gold handle doing?
- It turns a rotor (purple) that in turn spins the copper coil conductor loop (red line).
How about these red lines over here?
- Those show the circuit with a resistor (brown) that carries the current from the generator to the voltmeter (white).
What’s this white meter with the “V” on it?
- A voltmeter that registers the voltage.
What is happening in the black graph in the corner?
- It shows the changing voltage in the circuit.
Does the voltmeter have anything to do with the white dot traveling along the curve?
- The value on the voltmeter shows up as a white dot traveling along the curve.
(With Alternating current selected) Do you see a white dot anywhere else?
- Yes—on the spinning rotor. Its position on those spinning rings seems related to the value on the graph.
(With Direct current selected) How does the white dot in the graph relate to the spinning disks when this is simulating a DC generator?
- Whenever the black bar connects the two sides of the circuit, the circuit turns black and the voltage is at 0.
Have students adjust the values on the sliders and switches. After they are done, have them describe to one another how energy travels through the system. One possible description:
The handle is turned using kinetic energy from a person. That kinetic energy is transformed into rotational kinetic energy by the spinning disk. The copper and the magnet work together to transform the kinetic energy into electricity. The circuit picks up the electricity. The electricity moves through the meter and registers voltage.
Note that while you can toggle the rotational motion to pause or continue, this simply freezes the simulation. (The voltage would fall to zero as soon as motion stops.) Also, the simulation’s designer, Walter Fendt, explains "Instead of an armature with many windings and iron nucleus there is only a single rectangular conductor loop; the axis the loop rotates on is omitted."
Credit: Simulation adapted from Walter Fendt under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
Alternate simulation: if your electronic devices cooperate well with java, you may also introduce the generator using PhET’s generator simulation.