222 Common Science 



FIG. 124. Diagram of the complete 



through any or all of them at the same time and so 

 that shutting off one branch will not affect the others. 

 Electricians call this connecting in parallel; there are 

 many parallel circuits from one power house. 



Figure 125 illustrates the principle just explained. 

 As there diagramed, the electricity passes out from the 

 dynamo along the lower wire and goes down the left- 

 hand wire of circuit A through one of the electric lamps 

 that is turned on, and then it goes back through the 

 right-hand wire of the A circuit to the upper wire of the 

 main circuit and then on back to the dynamo. But 

 only a part of the electricity goes through the A circuit ; 

 part goes on to the B circuit, and there it passes partly 

 through the electric iron. Then it goes back through 

 the other wire to the dynamo. No electricity can get 

 through the electric lamp on the B circuit, because the 

 switch to the lamp is open. The switch on the C cir- 

 cuit is open ; so no electricity can pass through it. 



The purpose of the diagram is to show that electricity 

 from the dynamo may go through several branch cir- 

 cuits and then get back to the dynamo, and that shutting 

 off the electricity from one branch circuit does not shut 

 it off from the others. And the purpose of this section 



