PHY 2048L
Labs 1 and 3

Use of the Air Table

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Updated: 12/27/2008
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Caution

It is very important that you do not touch the hoses with your hands unless absolutely necessary. The oil from your hands will speed the degradation of the latex rubber used in the hoses and lead to air leaks. Use the plastic handle between the puck and the hose.

The sparks are created by high voltage pulsed DC, so you are strongly advised to avoid touching the puck itself while the spark timer is in operation. It will not kill a healthy person, but it is a severly shocking experience.

Do not remove the puck from the hose under any circumstances.

Contact the lab instructor if you have any problems with the apparatus.


Setup

See the lab description for information on what gets plugged in where. The basic idea is that you will use the power bar to turn on both the compressor and energize the timer when ready to do a measurement, and then hold the "foot pedal" closed whenever you want sparks made.

Your lab instructor will demonstrate this. Pay attention!

This photo shows a blank sheet of newsprint on top of the black conductive paper that covers the table. Notice that one corner is turned up and that one puck is down at that bottom corner. Only the other puck will move during the experiment.

air table ready for use

The electrical circuit for the sparks is made through the black paper from one puck to the other. The puck in the corner is put directly on the black paper so it has a better electrical contact.

Dark Spark Mark?

First, remember that the marks appear on the bottom of the paper. You see nothing on top. Second, how dark the marks will be depends on the timer you have. There is a tradeoff. Large dark marks are easier to see but are not as sharp when you go to measure their location. If you are not getting any marks, ask your instructor for help. It could be you do not have the equipment turned on, that you are not using the switch correctly, or that the silver chain that carries the electrical current is not making proper contact inside the puck because of how the puck was handled. The connections are checked before the lab starts, but can be disturbed when the puck is moved around when being weighed.

 
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 ?? Contact me if you have any questions.