Electromagnetic Qn. We put metal rods A and B in a Solenoid which is connected to battery cell.?

Question

After 'S' switch is closed, the metal rods roll away from each other. After some time , S is opened, rods rolls towards each other. The rods removed and the battery cell is replaced by sensitive galvanometer. S is closed. Explain how we can determine which is steel and iron?

Answer 1

While current flows, both rods are magnetized with the same polarity and so repel each other. After S is opened, current and magnetic induction fall to zero. The iron loses most of its magnetism relatively quickly, the steel retains more magnetism. The steel and the mostly unmagnetized iron attract each other. If you connect the galvanometer to the solenoid, you should see a weak kick or no kick when the iron rod is inserted and withdrawn quickly, and a stronger kick with the steel rod.