202 Our Surroundings 



The magnetic field is the space around a magnet which is 

 influenced by its force. 



The earth is a magnet of great size having a north and a 

 south magnetic pole. 



A dipping needle is a magnetized needle accurately balanced on 

 a horizontal axis. It is used to locate the earth's magnetic poles, 

 or to locate beds of magnetic ore. 



FACT AND THOUGHT QUESTIONS 



1. What is a natural magnet? An artificial magnet? 



2. Name some materials that are attracted by a magnet. 



3. Give several properties of a magnet. 



4. What is the largest magnet you have seen? 



5. How could you use a magnet to find a needle lost in a dark spot? 



6. Will a magnet pick up a tack from the bottom of a pail of water? 



7. State the law of magnetic poles. 



8. Describe the magnetic compass. 



9. Why is a magnetic compass uncertain and difficult to use on a steel 

 ship? 



10. What is induced magnetism? 



11. What is meant by a magnetic field? 



12. What are the properties of the dipping needle ? 



13. Is it always absolutely safe to depend on a compass? Why? 



PROJECTS 



1. Make an artificial magnet. Experiment with its lifting power. 



2. Make a dipping needle. Make a labeled drawing of it. 



OUTDOOR OBSERVATION 



1. Take a walk across country, or through a patch of woods, trying to 

 hold a straight course by a pocket compass. Observe and record diffi- 

 culties in doing this. 



2. Carry a pocket compass through a busy business street. Observe if it 

 is affected at all. Record your observations. 



REFERENCES 



The Wonder Book of Magnetism Houston 



Magnetism Houston & Kennedy 



