Question

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

• A. Straight lines perpendicular to the wire
• B. Straight lines parallel to the wire
• C. Radial lines originating from the wire
• D. Concentric circles centred on the wire

Answer 1

The correct option is D

Concentric circles centred on the wire

We can find the direction of magnetic field in a current carrying wire using Right Hand Thumb rule. Imagine you are holding a current carrying conductor with the right hand in such a way that the thumb points in the direction of the current. The direction in which the fingers encircle the conductor gives the direction of magnetic field. So, in this case the magnetic field consists of concentric circles centred on the wire.