write the help of an activity show that the electromagnetic property increases on cooling around a nail in an electric circuit
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Answer:
(1) Take a long insulated copper wire (The insulated copper wire should be quite thin).
(2) Also take a large iron nail.
(3) Wind the insulated copper wire round and round closely on the iron nail so that it may form a coil.
(4) Connect the free ends of the coil of wire to the two terminals of an electric cell through a switch.
(5) Switch on the current in the coiled wire by closing the gap in the switch. Now, place some steel pins near one of the ends of iron nail. We will find that the steel pins cling to the iron nail.
(6) The iron nail attracts the steel pins because the electric current flowing in copper wire coil (wrapped around it) has turned the iron nail into an electromagnet.
Switch off the current through the coiled wire by opening the gap in the switch. We will find that on switching off current through the coil, the steel pins get detached from the iron nail, they no longer cling to the iron nail. When current is stopped from flowing in the coil of wire, the iron nail no longer remains a magnet. Since the iron nail loses its magnetism, therefore, the steel pins do not cling to it anymore.
Thus, the iron nail behaves as a magnet only when electric current flows through the coil of insulated wire wrapped around it. When the electric current flowing in the coil is stopped, the iron nail loses its magnetism.