(N/A) To demonstrate this,we set up a circuit consisting of a battery $(12 \, V)$,a plug key $(K)$,an ammeter $(A)$,and a long thick copper wire as shown in the diagram.
$1$. Close the plug key $(K)$ to allow current to flow through the circuit.
$2$. Place a magnetic compass needle near the thick copper wire and observe its deflection.
$3$. Gradually move the compass needle away from the wire while keeping the current in the circuit constant.
$4$. We will observe that as the distance between the compass needle and the wire increases,the deflection of the needle decreases.
This observation confirms that the strength of the magnetic field produced by the current-carrying wire decreases as the distance from the wire increases.