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• Electricity : Flow of electric charge constitute electric current. It is Rate of flow of electric charge. It is denoted by I. Unit is Ampere ‘A’.
• Electric symbols –
  

  Electric Circuit Symbols

• Heating effect of electric current – Due to flow of current heat is generated in the conductor, this is known as heating effect of electric current. E.g. filament of bulb becomes hot when it starts producing light.
• Electrical fuse: Fuse are the metal wires which have comparatively low melting point than the circuit elements. Fuse is placed in series with the circuit element. In case of short circuit situation large current flows through the circuit. This causes heating of fuse wire thus fuse wire breaks and protect the circuit from damage.
• Magnet –
  • Has two poles
  • When suspended freely, north direction is north pole and south direction is south pole
  • Like poles of the magnet repel each other
  • Unlike poles of the magnet attract each other
• Needle of magnetic compass is a magnet
• Force from which magnetic needle deflects is called magnetic force
• Magnetic effect of electric current – when the current pass through the conductor, magnetic needle get deflected. It means that the current carrying conductor behaves as a magnet. It exerts magnetic force on the magnetic needle. Due to which it deflects. This effect is called magnetic effect of electric current.
• Electromagnet – Magnet that works on electricity
• Uses of electromagnet –
  • Crane lift heavy load
  • Help in separation of magnetic materials from scrap
• Watch complete video on electromagnet here
• 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.
  • Strip is kept in contact with the screw using a springy metal. The hammer is kept near the dome shaped structure called gong.
  • When switch is turned ON current flows through the coil making it an electromagnet. It attract the iron strip, so hammer moves and strikes the gong that produces sound. With this movement the iron strip goes away from screw and circuit breaks.
  • The current stops flowing and iron strip is not attracted. The springy metals brings the iron strip to its initial position and again the circuit get connected and current starts flowing.
• Watch complete video on electric bell here