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www.GOALias.blogspot.comcompass needle gets deflected when thecurrent flows in a nearby wire. Can youconnect the two observations? When thecurrent flows through a wire, does thewire behave like a magnet?This is what a scientist called HansChristian Oersted (Fig. 14.18) alsowondered. He was the first person whonoticed the deflection of compass needleevery time the current was passedthrough the wire.So, when electric current passesthrough a wire, it behaves like a magnet.This is the magnetic effect of the electriccurrent. In fact, an electric current canbe used to make magnets. Do you findit too surprising? Let us try it out.14.4 ELECTROMAGNETActivity 14.6Take around 75 cm long piece ofinsulated (plastic or cloth covered orenamelled) flexible wire and an iron nail,say about 6–10 cm long. Wind the wiretightly around the nail in the form of acoil. Connect the free ends of the wireFig. 14.19 An electromagnetRemember not to switch on thecurrent for more than a few secondsat a time. The electromagnet weakensthe cell quickly if left connected.to the terminals of a cell through a switchas shown in Fig 14.19.Place some pins on or near the endof the nail. Now switch on the current.What happens? Do the pins cling to thetip of the nail? Switch off the current.Are the pins still clinging to the end ofthe nail?The coil in the above activity behaveslike a magnet when electric current flowsthrough it. When the electric current isswitched off, the coil generally loses itsmagnetism. Such coils are calledelectromagnets. The electromagnetscan be made very strong and can liftvery heavy loads. Do you remember thecrane about which you read in Chapter 13of Class VI? The end of such a cranehas a strong electromagnet attached toit. The electromagnets are also used toseparate magnetic material from thejunk. Doctors use tiny electromagnetsto take out small pieces of magneticmaterial that have accidentally fallen inthe eye. Many toys also haveelectromagnets inside them.14.5 ELECTRICBELLWe are quite familiar with an electric bell.It has an electromagnet in it. Let us seehow it works.Fig. 14.20 shows the circuit of anelectric bell. It consists of a coil of wirewound on an iron piece. The coil acts168SCIENCE