Magnets are fancy of children. So many toys use magnets. However magnets have many applications. Magnet attracts iron, nickel and cobalt objects , the unlike poles of magnets attract each other however the like poles of magnets repel each other. Magnets are natural magnets (permanent magnets) and man-made magnets.
Earth as magnet –
A freely suspended magnet always point in the direction of north-south direction because earth acts as a magnet. This is shown in diagram. Due to south pole of the earth magnet, the north of the magnetic needle points towards north direction always. Therefore, it is clear that south of earth magnet lies towards north pole direction and north of earth magnet lies towards south pole direction. If we draw magnetic lines on a paper, all will be parallel and point towards north direction.
However, a Danish physics professor H.C.Oersted found that when current passes through a conductor, the magnetic field is generated around the conductor. This thing he found using magnetic needle. The magnetic needle got deflected when he passed current through a wire near the needle. The same effect as found by Oersted, is used in loading and transporting iron material. Sharp and heavy iron scrap material is attached to a big disc in which magnetism is induced with the help of electricity. Such a magnet is called an electromagnet.
Electromagnetism has application in electric water pump, electric generator, microphones, speakers, electric door bell, transformer, radio, television antenna.
Activity -1
Objective – To see the effect of magnetism of bar magnet on iron fillings/ to find magnetic lines of force around a bar magnet.
We put a white paper on a board, place a bar magnet on the paper. We sprinkle some iron powder on the paper and tap the board.
Observations
- Iron powder or iron filling is arranged in a regular pattern. The pattern has more iron fillings near the north and south poles of the magnet and it is on both side of the magnet.
- The pattern starts from north pole and ends at south pole of the magnet.
Conclusions
The iron filling on the board are arranged along the magnetic line of force as shown in fig.2. Because of magnetic lines of force around the magnet the iron fillings are distributed along the lines.
Read Next –
To draw the magnetic lines of force around bar magnet using magnetic needle.