Short Circuits

I never really understood short circuits and blowing fuses with too many things plugged in until I was 61 years old. Yes, I knew that the problem was too much electricity going through the wires, which would then get hot enough to cause a fire, so a fuse is installed with a soft metal that will melt and break the circuit before the rest of the wires heat up too much. Why does it get too much electricity, though? It is easy to see why a fuse would blow if something external introduced too much electricity to the system--- a lightning strike, for example. But what is the problem with too many appliances plugged in? Surely that would soak up more electricity, not introduce more of it. The appliances are consumers, not producers, after all.

But that reasoning is wrong. True, the appliance are users, not producers. But they are also, when turned on, new channels through which the electricity can flow. That's they key.

Start with the idea of how much electricity there is. That is called the charge, and is the basic scientific unit for electricity (measured in coulombs", a very ugly name).