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Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
A very simple, but absolutely fundamental, two part demonstration of magnetism, and electromagentism.
1. The classic experiment where a bar magnet is placed under a sheet of card, and iron filings are sprinkled down on it, so the magnetic field is made visible.
2. A simple solenoid is wound around a nail, and connected to an anlogue meter. When the solenoid is moved near the magnet still under the card, the meter will detect the presence of an electric current. When the solenoid is moved over an area where the iron filings bunch up around the magnet, the deflection of the meter will be seen to be larger.
Why does the magnetic field appear to reach out beyond the solid geometry of the magnet? How is the magnet able to affect the iron filings on the other side of the card? Is magnetism a force? Could the magnetic field be said to exist at all if there were no iron filings there to detect it?
Registered Member #16
Joined: Thu Feb 02 2006, 02:22PM
Location: New Wilmington, PA
Posts: 554
Sorry for vanishing from the thread there for a bit.
The 555 tone generator and LED blinker are both already standards in the course. I've found them indispensable for explaining wavelength, frequency, and oscillation.
I like the crystal radio project, it would be topical, but I'm concerned that we aren't getting deep enough in to electronics for them to understand the nitty gritty coolness of using a razor blade and a pencil as a rectifier. It might possibly be something I could do cheap enough for them to actually take the things home though. I need to look further in to it.
There is a merit badge booklet, but its been rewritten in the last 4 years or so, so its all modernized. Also, in typical fashion, it makes a really interesting subject insanely dry and boring. I usually use it for reference during the class, but I teach by an entirely different lesson plan that is much more interactive.
The electronic circuit build is the mid-point of the 8 hour class, right before lunch. They sit through all the dry electronics requirements in the morning, do the build to give them something fun to do, and get a better understanding of things while they do it, then after lunch do a bit more dry radio related stuff, then finish the class with at least 2 hours on the air.
I'm sorely tempted to make an attempt at a sort of group build of a Pixie II CW transceiver. I don't know how well it would play on a breadboard though. Maybe I'll just have to etch a PCB. Then they could actually make a contact with something they built.
I've taught this merit badge many times, I think a total of about 125 boys have gotten it from me, but I think I'm more excited about this group of kids than any group before. The average age is a little younger than usual, but they are all extremely enthusiastic, and crazy bright. That definitely means they're going to keep me on my toes, and I need some 'wow factor' to keep their attention.
Registered Member #2893
Joined: Tue Jun 01 2010, 09:25PM
Location: Cali-forn. i. a.
Posts: 2242
Oops, I forgot to rebuild the thing. Well it's simple enough, just build it on a breadboard and see for yourself. It's a perfect frequency demo IMO, and most importantly it's fun.
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Simple Demo Projects For 11-16 Year Old Newbies
