Exercises
1. Name an object whose usefulness depends upon its retentivity. Explain.
2. How do you explain the retentivity of hard steel?
3. Are the molecules of a piece of iron magnetized at all times? Explain.
4. When a piece of iron is magnetized by induction does any magnetism enter the iron from the magnet? Does the magnet lose as the iron gains magnetism? Explain.
5. Have all magnets been produced by induction? Explain.
6. Why will tapping a piece of iron when in a magnetic field increase the amount it will be magnetized?
7. Express in your own words the theory of magnetism.
8. Place two bar magnets in a line 5 cm. apart, unlike poles adjacent; obtain the magnetic field with iron filings. Sketch it.
9. Repeat Exercise No. 8 using like poles. Describe the appearance of a field that gives attraction; of a field that gives repulsion.