i could'nt understand oersted's expiriment and ampere's swimming rule.

Oersted's experiment

To describe this experiment, let us take a thick insulated copper wire and fix it in the north-south direction.Now a compass is placed near the wire.The two ends of this wire are connected to a battery through a switch.When no current is flowing in the wire,the compass needle is parallel to the wire(in the north -south direction).

Now, let us pass the electric current through the wire.We find that compass needle is deflected from it's original position and when the current is switched off the compass needle returns to it's original position.We know that a freely pivoted compass needle always sets itself in the north-south direction.It deflects only when it is acted upon by another magnetic field.

So,

In this experiment, Oersted showed that a current carrying wire produces a magnetic field which deflects the compass needle placed near the current carrying wire.


Ampere's swimming rule