Question

For a current in a long straight solenoid, $N$ and $S$ poles are created at the two ends. Among the following statements, the incorrect statement is:

• A. The field lines in a solenoid as well as a bar magnet form closed loops
• B. The strong magnetic field produced inside the solenoid can be used to magnetise a piece of magnetic material like soft iron, when placed inside the coil
• C. The magnetic field associated with the solenoid is different from the magnetic field around a bar magnet
• D. The N- and S-poles exchange positions when the direction of current through the solenoid is reversed.

Answer 1

The correct option is C

The magnetic field associated with the solenoid is different from the magnetic field around a bar magnet

A current carrying solenoid behaves like a bar magnet with fixed polarities at its ends. The field lines of a solenoid are also very much like that of a bar magnet, where it originates from the north pole and moves towards the south pole outside the magnet and moves from south to north inside the magnet. These field lines form closed loops. The N- and S-poles exchanges its positions when the direction of current through the solenoid is reversed.