In an earlier post, I described some of the "classic" examples that are used in physics classes. I was surprised when, in a lecture on transformers, the teacher didn't mention the role that transformers played in power transmission.
Turns out, I needed to be more patient. Yesterday, the teacher not only described, but actually demonstrated how transformers are used to deliver electricity over long distances. He set up a voltage supply to represent a power station, and a pair of lamps to represent different cities. First, he connected a lamp to the voltage supply, to show that it could light up. Then, he ran wires from the lamp to a pair of 1 kOhm resistors. He explained that if you want to run power over long distances, the resistance of wires becomes a problem. Between the resistors, he wired another lamp - which didn't light up. He increased the voltage so high that the first lamp blew out - to demonstrate that you can't just "up the voltage" and expect things to work out well for everyone. "Oh Noes!" Thought the class, "how will the people of second-lamp-ville get power?" Never fear, for SCIENCE is here!
Wolfi (our fearless teacher) then used transformers to step-up the voltage through the resistors, and then to step-down the voltage to the second lamp. Huzzah! Sweet, delicious electricity flows to the lamp, and they all lived happily ever after. The best part about all this is that the resistors were mounted on stands, so that the wires actually looked like power lines. Wolfi even told me there were covers for the lamps that made them look like houses.
It may not excite anyone else, but I think taking that extra step to make the power lines look like power lines made the demonstration really effective.