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

A thick insulated copper wire AB is placed in the north-south direction as shown in the figure. A plotting compass M is placed under the copper wire AB. Both the ends of the wire are connected to the battery with the help of a switch. The compass needle is parallel to AB when there is no flow of current. As the current flows through the wire AB, a small deflection is seen in the needle. Therefore, the deflection in the needle is used for detecting the magnetic field associated with an electric current.