Electric Current and its Effects Class 7 Science | Electromagnet and Electric Bell

Electric Current and its Effects Class 7 Science - Electromagnet and Electric Bell.
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When current flows through a conductor it behaves as a magnet. A magnet have very important property that it attracts iron. The coil behaves as a magnet when current flows through it however when current stops it loses its magnetism. Such coil is called an electromagnet. There are many uses of electromagnets. Cranes that lift heavy loads uses strong electromagnet , with the help of electromagnets it is possible to separate the magnetic materials such as iron from scrap material. An electric bell also uses electromagnet for its working.
Circuit of an electric bell : The coil wound over iron rods forms an electromagnet. A soft iron strip which have hammer at one side, is kept close to this electromagnet. Initially the strip is kept in contact with the screw using a springy metal. The hammer is kept near the dome shaped structure called gong. As soon as the switch is turned ON current flows through the coil making it an electromagnet. It attracts the soft iron strip and so the hammer strikes over the gong producing sound. However due to this movement the iron strip goes away from the screw breaking the electric circuit. So current stops and the coil does not attract the iron strip. The springy metal then bring the strip to its initial position i.e. again in contact with the screw. Again circuit is closed and electromagnets attracts the iron strip. Again sound is produced. This continues as soon as the bell button is pressed. By this way electric bell works.