184 



HOW WE PRODUCE ELECTRICITY 



darning needle, or a piece of watch spring about 3 inches long. 

 Make a paper boat about 4 inches long. Paraffin the outside 



and seams if made from 



magnetic, boat float- . ,-, ,, (-111 



pieces rather than folded. 

 After magnetizing the 

 steel, lay it in the boat 

 and cover with a thin 

 layer of melted paraffin. 

 Two such magnets may 

 be used if desired. On 

 the club race day have a 

 tub of water. Anchor 3 

 or 4 cork floats to mark 

 off the course. Boats 

 must go around the course 

 outside these floats. The 

 same magnet is to be used 

 by each contestant. This 

 should have a wire exten- 

 sion so that the magnet 

 can never be brought 



nearer than 6 inches to the boat. A stop watch is needed to time 



each boat, because each boat must be 



taken around the course by itself. The 



winner will be the one that makes it in 



the shortest time. 



3. How TO PRODUCE A MAGNET USING 

 ELECTRICITY 



(A) Connect a cell and push button 

 as shown in diagram. Bring a portion 

 of the wire down over and parallel to the 

 compass needle. Press the button to 

 cause an electric current to flow through 

 the wire. Result ? 



(B) Diagram B represents a wire 

 brought down over and parallel to the 

 compass needle. Complete the wiring 

 connections so that when the current 

 flows it will make the north pole of the 

 needle turn towards the west, as is rep- 

 resented by the dotted arrow. 



(C) Wind an insulated copper wire 

 in close layers around a soft iron rod, 

 remove the rod, connect the ends of the 



H button 



lie- 



B 



