Describe some experiment to show that the magnetic field is associated with an electric current.

We take a thick insulated wire AB and fix it in the north-south direction. Now, we place a plotting compass M under the wire AB. The two ends of the wire are connected to a battery through a switch.

Initially, when the switch is closed and there is no current flowing through the wire, we will fix the compass needle parallel to the wire in a north-south direction.

When current is passed through wire AB by closing the switch, we observe that the compass needle gets deflected from its north-south position. Again, on opening the switch, the compass needle returns to its original position.

Thus, in this experiment, the deflection of a compass needle by a current-carrying wire shows that an electric current produces a magnetic field around it. In other words, a magnetic field is associated with an electric current.