Points to Remember, Glossary, Concept Map

Points to Remember

• Magnets are classified into two types. They are: natural magnets and artificial magnets.

• Magnets attract things made of magnetic substances such as iron.

• The force of attraction of a magnet is maximum at the poles.

• A freely suspended magnet always comes to rest along the geographic north-south direction.

• Like poles of magnets repel while unlike poles attract one another.

• Materials which are attracted by magnets are called magnetic materials and those objects which are not attracted by magnets are called non-magnetic materials.

• Based on their behaviour in a magnetic field magnets can be classified as diamagnetic, paramagnetic and ferromagnetic materials.

• Depending on their ability to retain their magnetic property, artificial magnets are classified as permanent or temporary magnets.

• The south pole of the imaginary magnet inside the Earth is located near the geographic north pole and the north pole is located near the geographic south pole.

• In ancient times the magnet in the form of ‘direction stone’ helped seamen to find the directions during a voyage.

• Magnets, especially electromagnets are used in day to day life.

• Nowadays, magnets are used to generate electricity in dynamos.

• Magnets are used in computers in the storing devices such as hard disks. They are used in debit and credit cards also.

GLOSSARY

1. ALNICO An alloy of aluminium, nickel and cobalt.

2. Compass needle A needle (or plotting compass) which consists of a tiny pivoted magnet, usually in the form of a pointer, which can turn freely in a horizontal plane.

3. Magnet A piece of iron or other material, which can attract things containing iron.

4. Magnetic axis The line joining the magnetic poles.

5. Magnetic field The space around the magnet, in which the magnetic force is experiencedwithin a particular region.

6. Magnetism The branch of physics which deals with the property of a magnet.

7. Magnetisation A process in which a substance is made a permanent or temporary magnet by exposing it to an external magnetic field.

8. Magnetite A rock which has magnetic properties.

Concept Map

REFERENCE BOOKS

1. Electricity and Magnetism - Brijlal S. Subramanian - S. Chand publications

2. ICSE Physics - Lakmir Singh and Manjit Kaur - S. Chand publications

3. Physics concepts and connections - Art Hobson. Edition: Pearson Education

INTERNET RESOURCES

http s : / / w w w. l i ve s c i e n c e . c om / 3 8 0 5 9 - magnetism.html

https://en.wikipedia. org/wiki/Magnetar

https://www.investopedia. com/terms/m/ magnetic-stripe-card. asp