question_answer

Under what conditions permanent electromagnet is obtained if a current-carrying solenoid is used? Support your answer with the help of a labelled circuit diagram.  

Answer:

Under following conditions permanent electromagnet is obtained if current-carrying solenoid is used (i) The magnitude of direct current through the solenoid should be large. (ii) The number of turns in the solenoid should be large and closely packed, so that a strong uniform magnetic field inside it is produced. (iii) The rod kept inside is made of a magnetic materials such as steel.  (2)                                                           (1)