The term "short circuit" is a little confusing, in that electricity may have to go a longer way to be short circuited than to pass through some resistance, such as a lamp. Really a short circuit should be called an "easy circuit" or something like that, to indicate that it is the path of least resistance. Wherever the electricity has a chance to complete its circuit without going through any considerable resistance, no matter how _far_ it goes, we have a short circuit. And since everything resists electricity a little, a large enough flow of electricity would even heat a _copper_ wire red hot; that is why a short circuit would be dangerous if you had no fuses. _APPLICATION 59._ To test your knowledge of short circuits and fuses, trace the current carefully from the upper wire as it enters the laboratory, through the plug fuse. Show where it comes from to enter the plug fuse, exactly how it goes through the fuse, where it comes out, and where it goes from there. Trace it on through the cartridge fuse in the same way, through all the switches into the lamp socket, through the lamp, out of the lamp socket to the fuse gap, across this to the other wire, and on out of the room. It goes on from there through more fuses and back to the dynamo from which the other wire comes. Test yourself further with the following questions: 1. Where in this circuit is the resistance supposed to be? 2. What happens when you put a good conductor in place of this resistance if the electricity can get from one wire to the other without passing through this resistance? 3. Why do we use fuses? 4. What is a short circuit? 5. What makes an electric toaster get hot? 6. Why should you not stick pins through electric cords? EXPERIMENT 74. Take the fuse wire out of the fuse gap and put a single strand of zinc shaving in its place. Instead of the nail plug, screw the lamp into the socket. Do not turn on the switch that lets the electricity flow through the resistance wire, but turn on the electricity so that the lamp will glow. Does the zinc shaving work satisfactorily as a fuse wire? Now turn the electricity on through the resistance wire. What happens?