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 a straight line parallel to the wire
(C) The field consists of radial lines originating from wire
(D) The field consists of concentric circles centered on the wire

Answer 1

Hint
 When charged particles flow through a conductor, there will be a magnetic field formed due to the movement of charges. It is given that we have a long straight wire that produces a magnetic field. From the given statements we have to choose a statement that describes the direction of magnetic field lines correctly.

Complete Step by step solution
We have a straight wire and magnetic field lines. The direction of magnetic field lines is given by the right-hand grip rule.
According to the right-hand grip rule, if we hold a conductor in our right hand in such a way that the direction of our thumb will give the direction of the current through the conductor, then the direction of the magnetic field will be in the direction of our curled fingers.
Using this rule, we can say that the magnetic field lines will be in concentric circles around the conductor.

Option (D): The field consists of concentric circles centered on the wire

Note
There is another rule that we can use to get the direction of the magnetic field through a conductor. This rule is called Maxwell’s corkscrew rule. According to Maxwell’s corkscrew rule if we rotate a right-handed corkscrew in such a direction that the tip of the screw will be advancing in the direction of the current through the conductor and the direction of the rotation of the head of the screw will give us the direction of the magnetic field lines. In the case of the magnetic field and magnetic field lines, all the thumb rules that give us the direction of the force, current, and the direction of the magnetic field are very important