Three identical iron bars are kept on a table. Two out of three bars are magnets. In one of the magnet the North-South poles are marked. How will you find out which of the other two bars is a magnet? Identify the poles of this magnet.

We can find the other magnet with the help of magnet in which North & South poles are marked. Bring the marked magnet closer to the other two iron bars. Both the bars will be attracted towards the magnet as they are both made up of iron. So to test magnet, repulsion of like poles are to be used. Bring the poles of iron bars one by one towards the north pole of the magnet. The iron bar will be attracted but the actual magnet can get attracted or get repelled. Now change the poles of the iron bars. The magnet will be attracted/repelled but the iron will only be attracted.