state 2 ways by which the strength of an electromagnet can be increased.what type of core is used to make an electromagnet?state 3 differences btwn the electromagnet and permanent,

we can increase the strength of electromagnet by increasing the no. of turns in the coil and also by increasing the strength of current flowing in the coil.

soft iron core is used to make an electromagnet.

the three differences between electromagnet and permanent magnet is this that,

1> eletromagnet can be demagnetised easily by stopping the flow of current in it but in permanent magnet it cannot be.

2> electromagnet produces strong magnetic field but permanent magnet produces weak field.

3> the polarity of electromagnet can be reversed by reversing the direction of electric current through the solenoid but the polarity of permanent magnet cannot be reversed.