Describe an experiment conducted by Oersted to demonstrate that magnetic field is produced by electric current.

Explanation

Consider a wire PQ connected to a cell with a switch. Let a magnetic needle be placed below the needle. If the switch is opened, no deflection was observed. However if the switch is closed, then north pole of the magnetic is deflected whose direction is given by the right hand clasp rule.

If the magnitude of emf is increased, the deflection also increases. On reversing the polarity of the emf, the direction of deflection is also reversed. This experiment clearly demonstrates

the magnetic effect of electric current.