Demonstrate the separation of water molecule into constituent elements using electricity. This is particularly impressive if you can do with alternating current.
There's a cable sticking out the end of this building that needs a weatherproof light attached to it.
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"Did you get my e-mail?" - "The biggest problem in communication is the illusion that it has taken place" - George Bernard Shaw, 1856
Make a radar gun to measure the speed of vehicles. As a primary it would have a laser emitter which will sense the start of capture and end of capture by associated electronics.
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And then the God said" Let every drive be controlled by a PLC"