Question

describe an experiment to show the effect of current on a compass needle​

Answer 1

According to Faraday's first law when the magnetic flux linking a circuit changes, an electromotive force is induced in the circuit proportional to the rate of change of the flux linkage so if you hold a magnetic compass near a wire through which current is flowing, the needle on the magnetic compass will be deflected. Since compasses work by pointing along magnetic field lines, this means that there must be a magnetic field near the wire through which the current is flowing.

The law is proved by the above experiment.