==> physics/magnets.s <== Take the two bars, and put them together like a T, so that one bisects the other. ___________________ bar A ---> |___________________| | | | | | | | | bar B ------------> | | | | | | |_| If they stick together, then bar B is the magnet. If they don't, bar A is the magnet. (reasoning follows) Bar magnets are "dead" in their centers (i.e., there is no magnetic force, since the two poles cancel out). So, if bar A is the magnet, then bar B won't stick to its center. However, bar magnets are quite "alive" at their edges (i.e., the magnetic force is concentrated). So, if bar B is the magnet, then bar A will stick nicely to its end.