Question

Who discovered the magnetic effect of electric current?
(A). Oersted
(B). Newton
(C). Einstein
(D). Maxwell

Answer 1

Hint: The magnetic effect of current is the magnetic field developed around a current carrying conductor. An experiment was conducted in which a compass was moved near a current carrying conductor and deflections were observed in the needle of the conductor.

Complete answer:
Hans Christian Oersted, was a Danish scientist who carried out an experiment in which he used a compass and a current carrying wire.
He took a compass and moved it near a current carrying wire, when the compass was near the current carrying wire, its needle started deflecting.
He repeated the experiment with the same compass and the current carrying wire, but this time the current in the wire was flowing in the opposite direction. He moved the compass again towards the wire, but this time when the compass is near the wire, its needle starts deflecting in the opposite direction.
The deflections in the needle of the compass took place due to the change in magnetic flux associated with the needle. So, the deflections were observed when the compass was moving. We can conclude that the magnetic effect was developed due to change of electric flux associated with the compass.
This experiment led to the discovery of the magnetic effect of electric current.
Therefore, Oersted conducted an experiment which led to the discovery of magnetic effect of electric current.

Hence, the correct option is (A).

Note:
Flux is the number of electric lines of forces passing per unit area. Magnetism is developed due to change in flux. Magnetic field is a vector quantity. It exerts a force on other magnetic dipoles. The magnetic field around a straight current carrying conductor is represented by spherical closed lines of forces called magnetic lines around the wire.