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.

The magnetic field lines inside a solenoid are in the form of parallel straight lines. This pattern of field lines indicates that the strength of the magnetic field is uniform (same at all points) inside the solenoid.

Ways to increase the magnetic field strength of a current-carrying solenoid:

1. Increasing the number of turns in the solenoid.

2. Increasing the flow of current through the solenoid.

3. Using a soft iron rod as core in the solenoid.

A soft iron rod should be put inside a current-carrying solenoid to make an electromagnet because it can be magnetized and demagnetized easily.