• A magnet attracts the small pieces of iron.
• A freely suspended bar magnet, always rests in north south direction.
• A magnet has two poles north pole and South Pole.
• These poles exist in pair.
• Like poles repel each other, while unlike poles attract each other.
• A magnetic compass is a small magnetic needle pivoted at its Centre so as to rotate freely.
• It is used to indicate the north-south direction at a place.
• Repulsion is a sure test of a magnet.
• The space around the magnet in which the magnetic needle of the magnetic compass gets influenced is called the magnetic field of that magnet.
• Electromagnet is a temporary magnet which is made up of soft iron by the electrical method.
• An electromagnet acquires magnetism so long as current flows in the coil wound around a cylindrical tube. The strength of magnetic field of an electromagnet increases by three ways:
- By increasing the number of turns in the coil.
- By increasing the intensity of current in the coil.
- By inserting a soft iron core in the coil.
• The electromagnets are mainly used:
- To separate the iron from other substances
- To lift big pieces of iron scrap, girders, plates etc.
- To separate iron dust from wounds
- To load furnace with iron
- To obtain magnetic field in the electrical gadgets like electric bell, electric motor etc.
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Mark the poles of the given magnet.Marks:1
Due to the influence of earth’s magnetism, a freely suspended magnet always points in north-south direction.
Name the two important properties of a magnet.Marks:1
The two important properties of a magnet are
(i) Attractive property
(ii) Directive property
What name is given to the ore of the magnet?Marks:1
The ore of the magnet is called magnetite.
In which direction does a freely suspended magnet comes at rest?Marks:1
A freely suspended magnet always comes at rest in north-south direction.
Which portion of a magnet shows the maximum strength?Marks:1
The strength of a magnet is the maximum at its poles.