Final Presentation Layout/Notes for SSS '05

Two shows - 11 AM and 2PM, each 50 minutes long.

Very Attractive Science

We start with science that is attractive to the senses.

-- Main.JanineGoldstein - 21 Oct 2005


Topic for 2005: Electricity and Magnetism

Possible Names:

i.e., the Sun as an example of an enormous magnet and "a collection of magnets [i.e. the smaller magnetic fields]" We could do demos of magnetism, transition to a electricity format with Stella [William's Tesla Coil] and then do some electricity and magnetic levitation demos

Demo ideas

Links:

Windows to the Universe magnetism activities: http://www.windows.ucar.edu/tour/link=/teacher_resources/magnetism/teach_magnetometer.html http://www.windows.ucar.edu/tour/link=/teacher_resources/magnetism/teach_extension.html http://www.windows.ucar.edu/tour/link=/teacher_resources/magnetism/teach_terrabagga.html

And Randy has others. He's in charge of magnetism (for Windows, not general magnetism, as far as I know). These would all have to be modified if they were to be done with a large audience.

Quickie Demo's from ASTC via Linda - Janine 18 Oct 2005

Hi! They did two quickie demos at the ASTC showcase that might make good warmups, if not this year, sometime in the future. Both are "chemistry" demos:

1) Pour hydrogen peroxide (H2O2) into a small clear beaker

2) Fill a beaker with isopopyl alcohol

Linda

I just added this one That Teri Found - Tim 15 Nov 2004

This Week's Experiment - #401 Light Vibrations

For this one, you will need:

a nightlight with a clear bulb a strong magnet

Plug in the nightlight and turn it on. You will notice that the light is coming from a thin wire inside, called a filament. As electricity moves through the wire, some of the electrical energy is converted into heat. The wire gets hot enough to glow brightly.

Warning! This experiment may cause the light bulb to go bad, so be sure to have a spare handy.

Next, bring a powerful magnet near the bulb. Bring it as close to the filament as you can and watch closely. You should see the filament begin to vibrate rapidly back and forth. Why is it doing that?

Anytime electricity flows, it produces a magnetic field. If you have ever played with magnets, you probably know that every magnet has two ends, a north pole and a south pole. Two poles that are different will pull towards each other. Two poles that are the same will push away from each other. The electric field around the wire is interacting with the field of the magnet you put nearby. One part is pulled towards it, and the other part is pushed away.

But why is it vibrating? Because the flow of electricity in the wire is changing. You are lighting the bulb with alternating current. Just as its name suggests, alternating current alternates. It flows through the wires in one direction, and then it stops and flows the other way. Every time it reverses, the magnetic field reverses too. The north pole becomes the south pole. The part of the field that was being pulled towards the magnet is now being pushed away. Then the electricity reverses again, and it is again pulled towards the magnet.

Here in the United States, our electricity alternates 60 times every second. In some countries, it alternates 50 times per second, but either way, the experiment should work for you. If you don't see the vibration, try using a more powerful magnet or a different light bulb.

What would happen if you used a bulb lit by direct current? Direct current always flows in the same direction, so the magnetic field would be constant. The filament would not vibrate.

As I said earlier, this experiment may weaken the filament, causing the bulb to go bad. Have a spare bulb available, just in case, especially if this is the nightlight that you depend on for midnight ice cream emergencies.

How Toons 2/14/2005

From MIT. These are just plain cool!!!! http://www.howtoons.com

-- Main.JanineGoldstein - 20 Apr 2006

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