Uses of Electromagnets 225 



The Magneto. If the magnetic field in the generator is 

 produced by a permanent magnet, instead of by an electromagnet, 

 the machine is called a magneto. 



The Transformer. The transformer is a device for increas- 

 ing or decreasing the voltage, or pressure, of an alternating elec- 

 tric current. It consists of a core of layers of soft iron around 

 which are wound two separate coils of insulated wire. One coil 

 has more turns than the other. A current passing through the 

 coil of fewer turns magnetizes the soft iron core and the mag- 

 netized core induces a current of higher pressure in the coil of 

 many turns. This increase in 

 electrical pressure is called a 

 step-up in voltage. A current 

 passing through the coil of 

 many turns induces a current 

 of lower voltage in the coil of 

 few turns. This is known as 

 a step-down in voltage. 



The transformer makes it A SIMPLE ELECTRIC TRANSFORMER 



roccih1p tn etch ti h tVi^ irnlforrA * f ta ^ es a current of one strength and 

 pOSSlbj .0 Step-Up me VOltage, changes it to a current of greater or less 



or pressure, of the current strength. 



from a dynamo to so high a point that it easily overcomes the 



resistance offered by many miles of wire. Thus electricity can be 



sent long distances to points of use. At these points transformers 



step down the current to a pressure or voltage safe to use in our 



houses. 



The Big Creek Power Co., in California, is said to transmit 

 electricity of 160,000 voltage to Los Angeles, over 250 miles dis- 

 tant. The power plants at Niagara Falls transmit electricity of 

 high voltage to many cities and villages within a radius of over 

 150 miles. By means of transformers at the receiving end, it is 

 then stepped down and made available for use in running factories, 

 in lighting cities, and in other ways. 



The Electric Motor. The electric motor is a machine con- 

 structed somewhat like a dynamo. It is used to make something 

 move when it receives energy in the form of an electric current. 

 While the dynamo changes the energy of motion into electrical 



