Wednesday, January 21, 2009

Static Electricity

The following testimony took place between 3:04 P.M. and 3:17 P.M. on 1/16/09.

Donald Newcomer teaches sixth-grade math at Mount Vernon Middle School—his 31 year career in the Mount Vernon City School District includes teaching sixth-grade science.

Like eighth-grade science teacher John Freshwater, Newcomer used a Tesla coil during some of his lessons. Newcomer said that he used the device to help students to become excited. It was used during a unit on electricity.

Newcomer described touching the energized device like that of rubbing your feet on carpet and then touching something.

About 100 students touched the device during the times he demonstrated it—all willing volunteers, Newcomer said. The students would touch it with the tip of their fingers. Some students chose not to touch it.

The only times that he had it up to full voltage was when he would demonstrate with it by putting the tip of the device near the metal on the chalk board. When doing this he would sometimes turn off the lights in the room so the students could see the spark better, Newcomer said.

Like other teachers who have testified, Newcomer said that he has no safety concerns about the Tesla coil. Newcomer said he would not use the device if he thought it was going to hurt anyone.

Newcomer has two daughters that went through Freshwater’s class. His daughters never complained about Freshwater—one even recently commented to him about having liked Freshwater, Newcomer said.


The manufacture of the Tesla coil, Electro-Technic Products, Inc., gave this description of the device: “It has an output of between 20,000 to 45,000 volts, at a frequency of approximately 500kHz. When properly adjusted, when the electrode is held within ¼ to 1 in. (6 to 25 mm) from a metal object, a spark will jump to the metal. Current output of the spark is about 1 mA.”

High voltage is present anytime a spark is visible—even if it is a spark that resulted from walking across carpet and then touching a door handle. (The amperage of electricity is primarily responsible for injuries, not the voltage.)

The length of the spark is a good indicator of how high the voltage is. To learn more, visit the webpage by William J. Beaty “‘Static Electricity’ means ‘High Voltage’: Measuring your body-voltage.”

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