The magnetic field around a conductor changes in response to changes in what?

The magnetic field around a conductor changes in response to the current flowing through it. When an electric current passes through a conductor, it generates a magnetic field around it due to the moving electric charges. The strength and direction of this magnetic field depend directly on the magnitude and direction of the current.

If the current changes—either by increasing or decreasing—the associated magnetic field will also change proportionately. This principle is fundamental in electromagnetic theory and is applied in various electrical devices, including transformers and motors.

While voltage is related to current (as per Ohm’s law), it is the current itself that directly generates the magnetic field. Inductance is a property of a circuit or coil that opposes changes in current but doesn’t directly cause changes in the magnetic field. Frequency pertains to how quickly the current changes but also does not inherently change the magnetic field without varying current. Thus, current is the correct choice since it is the direct factor affecting the magnetic field.