33. Review; Magnetic Problems. To be sure that you understand and remember what was learned in [Exp. 11], do these problems:

1. Using the S pole of the horseshoe magnet, magnetize a needle so that its head will become a N pole. Test with floating cork, as in [Exp. 11].

2. Using the N pole of the horseshoe magnet, magnetize a needle so that its head shall be a S pole. Test.

3. Magnetize two needles, one on the N and one on the S pole of the horseshoe magnet, in such a way that the two points will repel each other. Test.

If the student cannot do these little problems at once, and test the results satisfactorily to himself, he should study the previous experiments again before proceeding.

Fig. 5.

Fig. 6.

EXPERIMENT 14. To find whether the poles of a magnet can be reversed.