Magnetism 201 



until the needle becomes vertical over the south magnetic pole. The 

 angle the needle makes with a horizontal line is called the dip of 

 the needle. The dipping needle is also used to locate magnetite, 

 a valuable iron ore. 



Experiment to Illustrate the Dipping Needle. 

 The action of the dipping needle may be illustrated with two 

 steel knitting needles, a cork, a large pin and two glass cups. 

 Thrust the needles half their length through the cork, at right 

 angles to each other. Set the cups a short distance apart. Use 

 one needle as an axis by resting its ends on the cups in such a 

 way that the other needle balances and points north and south. 

 If the other needle does not balance horizontally stick the pin in 

 the cork so as to make it balance. 



Remove the device from the cups and magnetize the balanced 

 needle. Replace the device in the same position. Does the mag- 

 netized needle remain horizontal? If properly adjusted, the N 

 pole of the magnetized needle will dip and the needle will make 

 an angle with the horizontal. 



SUMMARY 



There exists in some parts of the earth an ore that has the 

 power of attracting bits of steel and iron. This ore, which we call 

 lodestone, is a natural magnet. 



An artificial magnet may be made by rubbing a piece of steel 

 with a natural magnet or with another artificial magnet. 



A magnet possesses certain properties, such as polarity, power 

 to attract iron not magnetized, power to attract and repel 

 magnetic iron, and power to give magnetism to other pieces 

 of iron. 



The polarity of a magnet is its tendency, when suspended, 

 to point toward the north and south poles. 



The compass is an instrument used to aid in finding directions. 

 Its needle points north and south. 



Induced magnetism is the magnetism caused in a piece of iron 

 when it comes in contact with a magnet. 



It is believed that when a substance is magnetized its molecules 

 arrange themselves with like poles lying in the same direction. 



