College Physics 10th Edition by Raymond Serway,Chris Vuille

Exercise 38

Figure CQ19.16 shows four permanent magnets, each having a hole through its center. Notice that the blue and yellow magnets are levitated above the red ones. (a) How does this levitation occur (b) What purpose do the rods serve (c) What can you say about the poles of the magnets from this observation (d) If the upper magnet were inverted, what do you suppose would happen