Famous Science Problem

Famous Science Problem Solution - 7 May

You are in a room with no metal objects except for two iron  bars . Only one of them is a magnet.
How can you identify which one is a magnet?.

Update Your Answers at : Click Here

Solution

You can hang the iron bars on a string and watch which one turns to the north (or hang just one  bar).
Gardner gives one more solution: take one bar and touch with its end the middle of the second bar. If they get closer, then you have a magnet in your hand.
The real magnet will have a magnetic field at its poles, but not at its center. So as previously mentioned, if you take the iron bar and touch its tip to the magnet's center, the iron bar will not be attracted. This is assuming that the magnet's poles are at its ends. If the poles run through the length of the magnet, then it would be much harder to use this method.
In that case, rotate one bar around its axis while holding an end of the other to its middle. If the rotating bar is the magnet, the force will fluctuate as the bar rotates. If the rotating bar is not magnetic, the force is constant (provided you can keep their positions steady).