Under what condit

The conditions required to obtain permanent electromagnet when a current carrying solenoid is used are:

● The rod inside solenoid should be made of a magnetic material like steel, soft iron etc. This type of material can retain the magnetic properties for a long time after magnetization.

● Direct current should be used for solenoid.

● The turns should be closely packed and large in number for producing a uniform strong magnetic field

Fig. : A current carrying solenoid