Who Discovered the Magnetic Effect of Current?

Answer: Magnetic effects of current refer to the fact that current passing through a wire produces a magnetic field around it.

On April 21, 1820, Danish physicist Hans Christian Oersted discovered the magnetic effect of an electric current when he noticed that the needle of a compass near to a wire carrying electricity, rotated perpendicular to the wire. Oersted explored and discovered Oersted’s law, a physical law that describes the magnetic field. Oersted’s finding was the first of two laws that relate electricity and magnetism; the other being Faraday’s law of induction. These two laws become part of Maxwell’s equations, which regulate electromagnetic waves.

For a straight wire delivering a constant direct current (DC), Oersted discovered that:

• The current-carrying wire is encircled by magnetic field lines
• The magnetic field lines are parallel to the wire and lie in a plane perpendicular to it
• The magnetic field reverses direction when the direction of the current is reversed
• The size of the current is exactly proportional to the intensity of the field
• The field strength at any place is inversely proportional to the spot’s distance from the wire