UBC PHAS Demonstration Room Catalog

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====== Wimshurst Machine ======

{{tag> electricity_and_magnetism electrostatics leyden_jar generator high_voltage induced_charge located}}

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===== Description =====

Consists of a pair of counter-rotating plastic disks with copper sectors. On each side of the disk there's a pair of brushes oriented 90 degrees to the opposite pair of brushes. These brushes set up opposing charges on the disk once they are spinning and some collecting combs deposit that charge into a pair of Leyden jars. A pair of electrodes can be positioned a variable distance apart to discharge the machine at a desired potential. The entire machine is mounted on a wooden base with a metal frame, and has a crank to turn the discs. Another 'fuse' is present at the bottom of the machine to set an upper limit on the amount of charge that can be stored.

===== Purpose =====

Demonstrates a method of generating very-high-potential static charge using only counter-rotating disks with copper sectors and brushes. Provides a somewhat complicated example of induced charges, and can be used to illustrate the effects of static electricity. 

===== Apparatus =====

  * Wimshurst Machine

===== Setup =====

Simply place the machine on the table, remove any shorting wires (should there be any). Set the electrodes your desired distance apart, about 2cm works to start. You can start with them close together and move them further apart with the insulated handles to show how keeping them further apart will allow for greater charge buildup, but slower charging. Begin turning the crank counterclockwise. ((Only counterclockwise works. It seems like it should work both ways, but perhaps the brushes lose contact when you turn the other way.)) After some time you should begin to see and hear a spark jump between the electrodes. 

===== Notes =====

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**This demonstration involves high voltage.** It's very easy to get some quite unpleasant shocks from this demo so take caution. Short the electrodes together immediately before you touch the machine at all times. Additionally, take caution when setting the electrode distance. If the electrodes are left very far apart, it's not known how high the potential can get. Quite likely, much too high. Since it's a very small amount of charge at a very high potential we don't know exactly how dangerous this is, but you wouldn't want to find out first-hand.
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[[https://www.youtube.com/watch?v=Zilvl9tS0Og|Here]] is a great youtube video by MIT that explains the operation of this machine. 

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| **Location** | OPQ0 |
| **Maker** | Unknown |
| **Current State** | Working |
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UBC PHAS Demonstration Room Catalog

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