Wimshurst Generator (Paul DeCunzo)

Turn the handle and record the observations in the spark gap between the electrode distance. Vary the speed of the turning and/or the distance between the electrodes. Record your observations.

Place a piece of paper in the gap and run the machine. Record your observations.

Explanation

The Wimshurst influence machine is an electrostatic generator, a machine for generating high voltages developed between 1880 and 1883 by British inventor James Wimshurst (1832–1903).

It has a distinctive appearance with two large contra-rotating discs mounted in a vertical plane, two crossed bars with metallic brushes, and a spark gap formed by two metal spheres.

Static electricity is a non-moving electric charge. It is created by mechanically moving electrons from one place to another. If some material has free electrons (as most do) they will in general be evenly distributed on the surface along with positive charges in such a way the overall charge of the object is neutral. By rubbing two such materials together, however, it is possible to mechanically redistribute the electrons so they are, temporarily, unevenly distributed. When this happens, the object has a slight negative charge where the electrons are concentrated. If the tow objects have different amounts of free electrons, and single electrons (like charges) repel each other, some tof the electrons from the object with more electrons will be transferred to the other object

Questions

1. What parts on the machine specifically cause the spark generation? Answer: The brushes and metal rods collect the stray electrons.

2. What is the relationship between the gap distance and the size of the spark? Be specific. Answer: As the gap increases, the spark becomes longer and occurs less frequently.

3. Predict what will happen when a piece of paper is introduced into the gap. Answers will vary. Verify by experimenting.

Everyday examples of the principles illustrated

Lightening results from the static electrical discharge when clouds "rub" against each other.

Clothes stick together in the dryer or balloons to the wall.

You can discharge the static by rubbing your shoes on carpet and "shocking" your neighbor, especially in dry whether.