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 centred on the wire.
Answer
The field consists of concentric circles centred on the wire.
Explanation - When electric current is carried by a straight wire, it produces magnetic field lines in the form of concentric circles.