LABORATORY 



FACULTY OF AfWEO SC.ENCE. 



ELEMENTS OF 

 ELECTRICAL ENGINEERING. 



CHAPTER I. 



INTRODUCTION. 



ELEMENTARY ELECTRICITY AND MAGNETISM. 



1. The magnet. The name magnet was originally applied 

 to the lodestone, a mineral composed of iron oxide which, in its 

 native state, possesses the power of attracting iron. The lode- 

 stone imparts its magnetic property to pieces of iron or steel 

 which are brought near to it. Such pieces of iron or steel are 

 said to be magnetized and they are called magnets. The methods 

 at present employed for magnetizing iron or steel depend upon 

 the use of the electric current as described later. 



Poles of a magnet. Certain parts only of a magnet possess 

 the power of attracting iron. These parts are called the poles 

 of the magnet. The poles of a bar magnet, for example, are 

 usually situated at the ends of the bar. 



Compass. Naming of poles. A horizontal magnet free to 

 turn about a vertical axis places itself approximately north and 

 south. This fact is made use of in the compass, which consists 

 of a pivoted horizontal magnet playing over a divided circle. The 

 north-pointing end of a magnet is called its north pole and the 

 south-pointing end of a magnet is called its south pole. 



Mutual action of two magnets. The north pole of one magnet 

 attracts the south pole of another magnet, and the north poles 

 of two magnets or the south poles of two magnets repel each 



