How could you prove that an electric current produces a magnetic field?
Perform the following experiment to show that an electric current produces a magnetic field.
Place several magnetic compass needles in a circle, around a conducting wire which can carry current. Provide a switch so that the current through the wire can be switched on and off. See picture below.
As seen in picture (a), when there is no flow of current through the wire, all the compass needles point in the Earth's North pole direction.
Now switch on a strong current
The direction of such a magnetic field