Question

Which of the following correctly describes the magnetic field near a long straight wire?

• A. The field consists of straight lines perpendicular to the wire
• B. The field consists of straight lines parallel to the wire
• C. The field consists of radial lines originating from the wire
• D. The field consists of concentric circles centered on the wire

Answer 1

The correct option is D

The field consists of concentric circles centered on the wire

Magnetic field:

1. The magnetic field is defined as an invisible field that exerts a magnetic force on substances that are magnetism sensitive.
2. Magnetic field lines do not cross each other.
3. Magnetic field lines always make closed-loops.
4. The magnetic field lines always begin from the north pole and terminate at the south pole.
5. The density of the field lines denotes the strength of the field.

Magnetic field lines of a long straight wire:

1. The magnetic field lines of a long straight wire are comprised of concentric circles centered around the wire.
2. The direction of magnetic field lines is given by the right-hand thumb rule.

An illustrative diagram of magnetic field lines of a long straight wire:

therefore, from the above information of magnetic field lines of a long straight wire, option D is correct.