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

Question

(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 centred on the wire.

Answer 1

(d) The field consists of concentric circles centred on the wire.
On applying right-hand thumb rule, we find the direction of magnetic field. The field is in the form of concentric circles centred on the wire carrying current.
Hence, the option (d) is correct.