There is found on the earth's crust minerals called "lodestones", which exert magnetic forces and have "south poles" and "north poles". As with electric charges, like poles repel and unlike poles attract.

Diamagnetic objects are repelled by magnets and paramagnetic objects are attracted by magnets. Ferromagnetism is a special case of paramagnetism in which the magetic forces are especially large. Iron, nickle, cobalt, dysprosium, and gadolinium are ferromagnetic. Only a few substances are diamagnetic.

The earth behaves like a giant magnet with the south pole near the geographic north pole and the north pole near the geographic south pole. It is not known to this day, why the earth behaves like this.

  1. Explain the statement, "magnetic charges do not exist." What does this indicate about the cause of magnetism? What causes electrostatic forces?
  2. Why does a magnet attract a piece of iron, or other type of ferromagnetic substance?
  3. Contrast and compare electrical forces with magnetic forces. State what is the same about magnetic and electrostatic forces and what is different.
  4. A compass is a tiny magnet resting on a pivot so that it is free to rotate. Explain how a compass works. Why does it point to the geographic north pole?