3 Marks Question

Question 13 Marks

State two characteristic properties distinguishing the behaviour of paramagnetic and diamagnetic materials ?

Answer

Diamagnetic Substances	Paramagnetic Substances
1. They are feebly repeated by magnets.	1. They are feebly by attracted magnets.
2. On placing in an external field these substances acquire feeble magnetisation in opposite direction of the magnetising field.	2. On placing in an external field these substances acquire feeble magnetisation in direction of the magnetising field.

Question 23 Marks

Write two differences between electromagnet and permanent magnet.

Answer

Electro Magnet	Permanent Magnet
1. These can be magne-tised and demagnetised again and again.	1. These can not be magnetised and demagnetised again and again.
2. These are made of substances having high magnetic suspectibility and low retentivity e.g. Iron.	2. These are made up of sub-stances having high coercitivity and retentivity, e.g. steel or alloys.

Question 33 Marks

Compare the properties of soft iron and steel.

Answer

Soft Iron	Steel
1. Magnetic permeability is large.	1. Magnetic permeability is small.
2. Retentivity is less.	2. Retentivity is large.
3. Area of hysteresis loop is smaller.	3. Area of hysteresis loop is larger.
4. Coercivity is small.	4. Coercivity is large.

Physics 3 Marks Question