The earth's magnetic field, dip, declination, agonic line, induction by the earth's field.
Exercises
1. How would a dipping needle be of assistance in locating the magnetic poles of the earth?
2. Will a dipping needle weigh more before or after it is magnetized? Explain.
3. It is said that induction precedes attraction. Using this idea, explain how a magnet attracts a piece of soft iron.
4. Devise an experiment to show that a piece of iron attracts a magnet just as a magnet attracts a piece of iron.
5. Give two methods for determining the poles of a magnet.
6. State three of the most important points in the theory of magnetism. What evidence supports each?
7. Why is a permanent magnet injured when it is dropped?