ECC Physics

Location:

Phys 104 (Lobby) above bookcase

Alias:

Pulse Glass

Light Powered Teeter-Totter

Location:

105-782

Description:

Model ES-9054B Electrometer can be used to measure charge, voltage, and current. Combined with the Model 9043 Precision Variable Capacitor at 5ST-785 shows the voltage stored between 2 charged plates can be changed by the distance the 2 plates are apart.

Links:

Model 9054B Electrometer

Model 9043 Precision Variable Capacitor

Electrometer in use

For storage have wax paper

Cat Fur & Rubber Rods

Location:

5ST-711

Description:

Rubbing the cat fur and rubber rod together, the cat fur will give electrons to the rubber rod. Thus making the rubber rod negatively charged.

The Card

Taking a 4″x6″ paper card, fold the short ends a centimeter in and place on a flat surface with the ends sticking down. Blowing on it with the open end facing you, the card will not move backward. But facing one of the ends the card will move backward when blown on.

The Paper

Holding a normal 8.5″x11″ piece of paper on the bottom, blow across the top. The paper will rise due to the pressure gradient.

Aliases:

Plexiglas, Limacryl, R-Cast, Perspex, Plazcryl, Acrylex, Acrylite, Acrylplast, Altuglas, Polycast, Oroglass, Lucite, Acrylic Glass

How to Remove Old adhesive Paper From Acrylic Sheets

Get a pane of glass larger than the acrylic you are working on. Spray Denatured Alcohol on one side of the acrylic with the adhesive paper and on the glass where you will put the alcohol soaked acrylic side. Leave for 30 to 45 minutes. After the allotted time the paper should be easy to peel off. Any stubborn pieces that do not peel off easily can be left to soak a second time or scratched off with a fingernail usually.

After the paper is fully removed quickly run water over it to wash off the alcohol and diluted adhesive. Then dry off the acrylic with paper towels to check for any spots of adhesive. If not done quickly enough the alcohol will evaporate and the adhesive will stick once again. Once it starts sticking after the first time, just put alcohol on the adhesive and rub off, making sure to quickly wash off as well and then drying so water does not leave any spots as well.

Flame Polishing

WARNING: Only flame polish in a well ventilated area because the fumes given off from heated acrylic are toxic.

Before flame polishing it is best to get the surface as smooth as possible. This can be done in several ways with varying degrees of success. Using a jointer is the best way if exact 90° angles are a necessity. Using a smooth file works as well, the finer the teeth the finer the finish after the flame polishing. Also sandpaper works, starting from a rough 80, dropping all the way to 330.

I have found that Bunsen burners do not work for flame polishing, a propane torch does though. After lighting the propane torch, adjust it to a blue almost invisible flame. Then with steady passes over the surface, the acrylic should show a glass smoothness. Use the propane torch immediately over any problem areas to pinpoint areas that did not become smooth.

Acrylic Troubles

Flame polishing very thing pieces of acrylic causes the acrylic to bend and contort which can be problematic for a final product.

Location:

Phys 105 stockroom above the 340 and 440 section of aisle (may look like a support for the tubes above)

Description:

1″x1″x49″ aluminum bar, 49″ ~ 124cm.
Requires the hammer with acrylic head in the Phys 105 stockroom (105-430).

This demo is to show an object can have multiple natural frequencies. Holding the bar up and hitting it in different places can produce various pitches (you can also hold it in different places). The practical application of this is in the musical bars.

Another demo for natural frequency is getting 2 metal tools (a crescent and combination wrench) that weigh about the same. Hiding them, drop one and ask whether the class can figure out which one was dropped just by the sound.

124 cm Aluminum Bar

^_^