Sound and Waves

It turns out that we had it right when we were 8; a cup and a string make for an excellent telephone, and for one hell of a physics lesson on sound, waves, and resonance.

If you get the chance, procure some really thin wire. You know, the kind that those movie tough guys are always strangling people with. If you have two Tim Hortons coffee cups, and one really long hallway, you can demonstrate so many of the wonderful aspects of sound, waves, and vibrations it is unbelievable.

Note, some old coffee cans work a bit better, but are a tad harder to come by. The perk (sigh) of the coffee cans, is that you can (after poking small holes in the bottoms and tying knots in the wire to prevent it from coming out) get some pretty good tension in the wire, making it work a bit better. The coffee cup bottoms (cardboard) tend to rip when you pull hard.

Materials and Set-up:
Two cans/cups with bottoms that you can poke a small hole in (without bending the bottom -- try using a drill or screw if using metal coffee cans. With a cardboard cup, the wire may do the trick -- if not, use a pin)
Thin wire (I used 30+ meters)
Long Hallway
Radio (not required, but cool)

Some crazy cool things you and your students (or children) might observe:
1. The sound is AMAZINGLY clear over such a long distance
2. You can talk fairly quietly. The cup you hold amplifies your signal, and the one at the other end boosts it again
3. You can hear the person through the cup WAY before you can hear them through the air (if you can hear them through the air at all!)
4. You can hear the radio clearly through the apparatus as well (yeah, I know, not groundbreaking, but who doesn't love a little Katy Perry)
5. You can have students stationed along the wire (which I recommend so people don't walk into it) and have them pluck the string producing guitar like sounds on both ends. Pluck at different places or at multiple places at once.

All of these things can lead to rich observations and discussions about:
transmission of energy through a medium
the nature of sound waves
the speed of sound (solid vs gas)
resonance (in an air column, on a string, or in general)
the human ear
interference of waves
intensity of sound and the decibel scale
whether Katy Perry is better than Michael Jackson, or if her parallel success to his is a sign of the times and speaks to a lack of true artistic talent

and maybe lots more that I am missing

This upcoming semester, I plan to start with sound so I don't have to rush through anything and we can explore these ideas to our ears content.