CHAPTER XI 

 ELECTRICITY 



USE OF ELECTRICITY IN THE HOME 



Measuring of Electricity. The gas supplied to a home is meas- 

 ured in cubic feet. This gas is consumed, and the products of com- 

 bustion escape into the atmosphere. Electricity, however, is not 

 consumed, but merely flows through the lamps, motors or other 

 appliances, and passes back to its source, the electrical generator. 

 We really, then, do not use electricity, but simply the energy which 

 the moving electricity possesses. This energy is sufficient to pro- 

 duce light, heat and power by allowing it to flow through a lamp, 

 a heating device, or a motor. Electricity may be compared to water 

 circulating through pipes. 



Suppose in some centrally located place there were a station 

 provided with a large water pump which pumped a supply of water 

 to the buildings of the town. Assume that all the water of that 

 place was used to run through some type of machine, such as a 

 motor, and that all the water, instead of running into a sewer, was 

 drawn back through another pipe to the pump and then sent out 

 again. The water would be continually circulating from the pump 

 to the motor through the meter and back to the pump. A person 

 supplied with this water would not be using the water itself but 

 the energy which it was able to deliver to the machine. This energy 

 could not be measured in gallons because the energy would depend 

 upon the difference of pressure between the inlet to the water motor 

 and the outlet. If there were a great difference, the motor would 

 run very fast and do a great deal of work at the same time. A great 

 amount of water would flow through the motor. A meter would 

 then have to be constructed which would measure the amount of 

 water flowing through the meter per second, and the difference in 

 pressure in pounds per square inch. 



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