ELECTRIC BELL 



1983 



ELECTRICITY 



taining a solution of sal ammoniac, next some 

 manganese dioxide in the form of a black 

 powder, and within this a strip of carbon. The 

 sal ammoniac acts on the zinc when the cell 

 is producing a current. The manganese dioxide 

 is a depolarizer which slowly removes the 

 hydrogen from the carbon after the cell has 

 polarized. The Le Clanche cell consists of zinc 

 and carbon plates in a solution of sal ammo- 

 niac. E.E.B. 



ELECTRIC BELL, a bell that is rung by 

 electric energy. The door bell is the most 

 common illustration of bells of this type. The 

 apparatus consists of an electromagnet s, an 

 armature b, to which the clapper is attached, 

 a spring that 

 pushes against 

 the screw c, and 

 the gong d. The 

 battery is usually 

 placed in the 

 basement and the 

 wires connect it 

 with the push 

 button at the 

 door, which is it- 

 s e 1 f connected 

 with the bell. 

 When the button 

 is pushed the cir- 

 cuit is completed 

 and the current THE ELB CTRIC BELL 



flows along the The various parts are ex- 

 plained in the text, 

 wire a and over 



the coils ss, magnetizing the core. The mag- 

 net attracts the armature b and causes the 

 clapper to strike the gong. This movement 

 removes the spring from contact with the 

 screw and breaks down the circuit, so that 



the armature is released and moves back to 

 its former position, which brings the spring in 

 contact with the screw and again closes the 

 circuit, so that the bell continues to ring as 

 long as the pressure on the button is main- 

 tained. Any number of bells connected with 

 the circuit may be rung by the same push but- 

 ton. 



When electric bells get out of order the 

 trouble is likely to be with the battery-, which 

 is weak. If, however, the battery proves to be 

 in good condition one should look at the adjust- 

 ment of the screw with the spring c. Con- 

 tinuous use may jar the screw out of position 

 so that the spring fails to make connection with 

 it. A slight turn of the screw is all that is 

 necessary to set matters right. See ELECTRO- 

 MAGNET. W.F.H. 



Consult White's Electric Belli, Alarms and 

 Signaling System*. 



ELECTRIC HEATING. The production of 

 heat by electricity depends on the fact that 

 materials of high resistance are heated to a 

 higher temperature by an electric current than 

 materials of low resistance. This is shown by 

 the fact that the wires in an electric water 

 heater or an electric toaster become red hot, 

 while the copper wires which conduct the cur- 

 rent to the heater are scarcely warmed. Both 

 wires carry the same current, but one having 

 much greater resistance than the other is heated 

 to a much higher temperature. For the same 

 current the quantity of heat produced in a 

 given time is proportional to the resistance; 

 the temperature can be regulated by adjusting 

 the resistance. Electric heaters for street caw 

 and for houses are adjusted to produce suffi- 

 cient heat to warm the air, but not to so high 

 a temperature as that required for cooking. 



THE STORY OF ELECTRICITY 



LECTRICITY, e lek Iris' i li, the 

 agency which is known to people through a 

 variety of effects commonly called electrical. 

 The action of electricity is well understood, 

 but very little is known of its nature. We 

 know well what it does, but not what it is. 



The world has been more thnn 2..'jOO year* 

 in securing its present knowledge of electricity 

 and electrical effects, and nearly all of our 

 knowledge has come to us within a period of 

 300 years. Indeed, it can be said that the 

 practical application of electricity to the needs 



