_. ;:s , ; ... , : . -96 



What does a deflection of the galvanometer needle in- 

 dicate ? 



State clearly how an electric current may be produced 

 by the aid of magnets. 



FIG. 72. In the dynamo motion is supplied and electricity results. 



The Telephone. Place a magnet within a coil of wire 

 which is attached to a galvanometer as before. Bring a 

 piece of soft iron toward the magnet. Does the approach 

 of the magnet cause a deflection of the needle ? Withdraw 

 the soft iron. Does the withdrawal of the magnet cause 

 a deflection of the needle ? 



Why should the approach and withdrawal of the iron 

 produce a current of electricity ? 



Explain how this principle is applied in the telephone. 



