Which of the following statements is/are correct for a current carrying solenoid?
(i) It can be used to magnetise a piece of soft iron.
(ii) It acts like a bar magnet
(iii) The field lines are concentric circles

Correct option is D

A current-carrying solenoid generates a magnetic field similar to that of a bar magnet. It has distinct north and south poles, and the magnetic field inside the solenoid is uniform, while the field outside it behaves like that of a bar magnet.

• Statement (i): A solenoid can magnetize a piece of soft iron by inducing a magnetic field in the iron, making it act like a temporary magnet. This is true.
• Statement (ii): The magnetic field around a current-carrying solenoid behaves exactly like the magnetic field of a bar magnet, with a well-defined north and south pole. This is also true.
• Statement (iii): The field lines inside the solenoid are parallel and straight, not concentric circles. Outside the solenoid, the field lines resemble those of a bar magnet, not concentric circles.

Thus, statements (i) and (ii) are correct.

Important Key Points:

1. A solenoid is a coil of wire, usually wound in a cylindrical shape.
2. When current flows through a solenoid, it creates a magnetic field similar to that of a bar magnet.
3. The magnetic field inside a solenoid is uniform, while outside it, the field resembles that of a dipole.
4. The strength of the magnetic field inside a solenoid can be increased by increasing the number of coils or the current.
5. A solenoid can magnetize a piece of soft iron by placing it inside the solenoid.
6. The magnetic field outside the solenoid forms closed loops and looks like the field around a bar magnet.

Information Booster:

• The magnetic field lines inside a solenoid are parallel and uniform, unlike the circular pattern outside.
• Soft iron is often used inside solenoids for electromagnets due to its high magnetic permeability and the ability to be magnetized easily.