Which type of electrical current constantly changes direction, causing the magnetic field to change?

Which type of electrical current constantly changes direction, causing the magnetic field to change?

• A. Direct current (DC)
• B. Pulsating direct current (PDC)
• C. Alternating current (AC)
• D. Static current

Answer: (C)

The magnetic field around a conductor follows the current and its direction. Direct current flows in one direction, so the magnetic field is steady in direction (though its strength can change with load). Pulsating direct current also keeps the same direction, so the field changes in magnitude but not in direction. Static current means no change over time, so there’s no changing magnetic field at all. Alternating current reverses direction repeatedly, so the magnetic field around the wire flips as well. That continuous reversal is what makes the magnetic field change direction over time. The rate of reversal is the frequency of the current, which is why AC power systems and devices rely on alternating current.

The magnetic field around a conductor follows the current and its direction. Direct current flows in one direction, so the magnetic field is steady in direction (though its strength can change with load). Pulsating direct current also keeps the same direction, so the field changes in magnitude but not in direction. Static current means no change over time, so there’s no changing magnetic field at all. Alternating current reverses direction repeatedly, so the magnetic field around the wire flips as well. That continuous reversal is what makes the magnetic field change direction over time. The rate of reversal is the frequency of the current, which is why AC power systems and devices rely on alternating current.