What type of magnetic field lines are produced by a current going down a straight wire?

When a current flows through a straight wire, it generates a magnetic field that circles around the wire. This phenomenon is a consequence of Ampère’s circuital law, which states that a magnetic field is produced by electric currents.

The magnetic field lines created by the current in the wire are circular in shape. Specifically, if you visualize the wire in three dimensions, the circular magnetic field lines extend outward from the wire in concentric circles. The direction of these circular lines can be determined using the right-hand grip rule; if you hold the wire with your right hand, with your thumb pointing in the direction of the current, your fingers will curl in the direction of the magnetic field lines.

This specific arrangement of circular lines around the wire indicates that the magnetic field strength diminishes with distance from the wire; it is strongest right next to the wire and weakens further away. This understanding of magnetic fields is crucial in various applications, such as in electromagnets and the design of electrical circuits.