Q23 of 72 Page 13

Distinguish between a bar magnet and an electromagnet.


S.No.Bar MagnetsElectromagnets
1.The bar magnet is a permanent magnet.An electromagnet is a temporary magnet.
2.It produces a comparatively weak force of attraction. It produces a very strong magnetic force.
3.The strength of a bar magnet cannot be changed.The strength of an electromagnet can be changed by changing the number of turns in its coil or by changing the current passing through it.
4.The polarity of a bar magnet is fixed and cannot be changed.The polarity of an electromagnet can be changed by changing the direction of current in its coil.
 

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21 How will you find out the direction of the magnetic field produced by current-carrying conductor? 22 What type of core should be put inside a current-carrying solenoid to make an electromagnet? 24 State the composition of the alloy called nipermag? Give an important use of this alloy. 25 Derive the formula for the force acting on a charged particle moving in a magnetic field.