Having been through science fairs with child #1 and child #2, I should be an old pro. Instead, these middle school rituals teach me how little I know about basic scientific principles.
Like electricity.
Apparently, there’s this equation V=I*R (or R=V/I, or I=V/R) that has the same importance to electrical engineers as E=MC2 has for physicists. Well it doesn’t mean much to me. So when Child #3 (C3 hereafter) says he wants to study the effects of temperature on the conductivity of wire, I say, “Cool. How do you do that?”
“Run the same amount of volts through a hot wire, a cold wire, and a room temperature wire and measure the current.”
“Great,” I say. “Let me know if you need help formatting the report.”
Needless to say, I got dragged in well before the report was written. We set up a cool little base with a battery pack and some screws to connect the wires. C1 soldered some alligator clips to the screws.
The first of our many problems was not having enough wire. We were using 6″ sections, and the difference in resistance simply wasn’t measurable in that small of a section. Then it turns out that thick wire doesn’t have as much resistance as thin wire. My father-in-law had a bunch of thermostat wire laying around, and I thought we could keep our costs down by using it. No dice. Another trip to Radio Shack.
In the end, it was a pretty good experiment. C3 had hypothesized that the hot wire would conduct better than the cold wire on the grounds that the fast moving atoms in the wire would help shove the current along more quickly. Turns out he was exactly wrong, but he found out by measurement and observation (and quite a bit of trial and error), which is the whole point of the thing after all.
