WCCS science class a ‘dynamo’ team
It’s a fundamental law of physics, you can’t get more energy out of a system than you put in.
Fourth, fifth and sixth grade students at Warren County Christian, while working with solar power, posed a question. Would another motor increase the voltage coming out of the system?
Teacher John Lewis decided to let them test the theory.
The students took a battery with a measurable output of 1.5 volts, hooked it to a motor, added a coupling, threw in another motor facing it and measured the results.
They had more than 1.5 volts and they also had questions.
“It grew from there,” Lewis said. “I kind of let them run with it.”
Students started making adjustments to the system and taking measurements.
The coupling on the system was originally just a plastic fan, so students removed the fan blades from the coupling to test the results. Without the wind resistance from the blades, the system ran faster and, not having a stationary mounting, gained stability. The voltage also increased again. This time to more than two volts.
“When you have fan blades,” student Ryan Weidner explained. “It pushes air down and slows it down.”
“By chopping these off it makes more voltage,” student Ben Gibson added.”
To demonstrate, students illuminated an LED light with the system that the battery alone was incapable of lighting.
“We’ve learned that different things, if they’re heavier, they run differently,” student Lily Lauffenburger said.
Students wrote papers on why they thought there might be an increase in voltage. They weighed system components and took apart the two motors, measuring the wires inside with micrometers.
“We try to keep them doing activities and asking questions,” Lewis said. “If they’re asking questions, they’re thinking at a higher level than if you’re just feeding them information, and this generated a lot of questions.”
They found one of the motors had three times as much wire inside but had much thinner wiring than it’s companion of the same weight.
From there they discovered that what they had wasn’t a machine capable of violating the laws of thermodynamics, but a dynamo.
A dynamo utilizes a conductor, in this case metal wire, and magnetic field generation, in this case from the motors, to generate a direct current. The pulsation of the magnetic field over a conductor generates voltage.
Once they realized this, students measured the magnetic field, and accounted for the increased voltage.
Lewis also brought up the experiment when he spoke with Dan Hoden, who works with electrical component supplier Rexnord. Hoden took the initiative to provide two professional grade couplings courtesy of Rexnord.
The couplings, worth approximately $50 each, are part of the focus of students experiments going forward. They will be seeing how the higher-grade couplings effect system output, in light of higher efficiency but also of increased weight.
“It gave them an opportunity to intermix with a local business,” Lewis said. “It gave them an opportunity they wouldn’t have in education normally.”