Question

Assertion (A): When a current is switched on in a circuit with a wire, a magnetic compass placed near it gets deflected. Reason (R): A current-carrying wire produces a magnetic field.

In 1820, Hans Christian Oersted discovered that a magnetic needle is deflected by a current-carrying wire. For many years, he had expected to find a connection between electricity and magnetism. Before his discovery, Oersted had imagined the magnetic field to be a straight line along the direction of the wire - with the north pole at one end and the south pole at the other. This was a major reason why he took so long to discover electromagnetism. The figure below shows how Oersted would have arranged his wire and magnetic needle in his early experiments.