Electricity 245 



it is the path of least resistance. Wherever the elec- 

 tricity 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 every- 

 thing 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 



