Electricity 255 



FIG. 143. The bell is rung by electromagnets. 



The electric bell, like the telephone and telegraph, 

 works on the simple principle that electricity flowing 

 through a wire that is wrapped around and around a 

 piece of iron will turn that piece of iron into a magnet 

 as long as the electricity flows. 



The electric motor. The motor of a street car is a 

 still more complicated carrying out of the same prin- 

 ciple. In the next experiment you will see the work- 

 ing of a motor. 



Experiment 79. Connect the wires from the laboratory 

 battery to the two binding posts of the toy motor, and 

 make the motor run. Examine the motor and see that it 

 is made of several electromagnets which keep attracting 

 each other around and around. 



Motors, and therefore all things that are moved by 

 electricity, including trolley cars and electric railways, 

 submarines while submerged, electric automobiles, elec- 

 tric sewing machines, electric vacuum cleaners, and 

 electric player-pianos, are moved by magnetizing a 



