vii.1. Magnetic Effect of Electric Current: Oersted’s Magnetic Revelation

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vii.1. Magnetic Effect of Electric Current: Oersted’s Magnetic Revelation

If the electric current passes through a wire, then the current carrying wire behaves like a magnet. Hans Christian Oersted (A.D. 1777-1851) was the first person who noticed that every time when the current was passed through the wire the compass needle placed near it got deflected from its usual North-South position.

Magnetic Power: Electromagnets in Action and Practical Uses

- It is a magnet made by passing electric current through it.
- Electromagnet consists of a coil of insulated wire wrapped around a piece of iron which is magnetised only when an electric current is passed through the coil.
  - The magnetism of an electromagnet remains as long as the current is flowing in its coil.
Uses

The electromagnets can be made very strong and can lift very heavy loads.
The electromagnets are also used to separate magnetic material from the junk.
Doctors use tiny electromagnets to take out small pieces of magnetic material that have accidentally fallen in the eye.

Electric Bell: How Electric Bells Ring and Reset?

Electric bell consists of a coil of wire wound on an iron piece.
- The coil acts as an electromagnet.
Working: An iron strip with a hammer at one end is kept close to the electromagnet.
- There is a contact screw near the iron strip. When the iron strip is in contact with the screw, the current flows through the coil which becomes an electromagnet.
- It, then, pulls the iron strip and the hammer strikes the gong of the bell to produce a sound.
- However, when the electromagnet pulls the iron strip, it also breaks the circuit and the current through the coil stops flowing.
- The iron strip comes back to its original position and touches the contact screw again. This completes the circuit.

The current flows in the coil and the hammer strikes the gong again.
This process is repeated in quick succession.

Did You Know

The credit for the invention of the electric bulb is usually given to Thomas Alva Edison (A.D. 1847 – 1931), though others before him had worked on it. He was a remarkable man. He made some 1300 inventions including the electric bulb, gramophone, the motion picture camera and the carbon transmitter, which facilitated the invention of the telephone.