Q.Who discovered the magnetic effect of current?

A moving charge produces both an electric field (due to its charge) and a magnetic field (due to its motion/current).

A stationary charge produces only an electrostatic field around it, given by Coulomb's law. A moving charge, in addition to still possessing this electric field, constitutes a tiny current element (since current is charge in motion), and according to the Biot–Savart law every current element produces a magnetic field around it. This is the basis of electromagnetism: electricity and magnetism are linked through charge motion. This is precisely why a current-carrying co …

Hans Christian Oersted discovered the magnetic effect of electric current in 1820.

In 1820, the Danish physicist Hans Christian Oersted observed, during a lecture demonstration, that a compass needle placed near a current-carrying wire got deflected. This showed for the first time that an electric current produces a magnetic field around it — the magnetic effect of current. This discovery laid the foundation of electromagnetism, later developed mat …