When the current in the copper wire is increased, the deflection of the compass needle also increases. This behavior is a result of the relationship between electric currents and magnetic fields, described by the right-hand rule and Ampere’s Law.

An increasing current in a straight conductor produces a stronger magnetic field around the conductor. The magnetic field lines form concentric circles around the wire. When a compass needle is placed in this magnetic field, it aligns itself with the field lines. As the current increases, the magnetic field becomes more intense, causing a greater deflection in the compass needle.

In summary, an increase in current through the copper wire results in a stronger magnetic field around the wire, leading to an increased deflection of the compass needle placed in proximity to the wire. This phenomenon is a fundamental principle in electromagnetism and is essential for various applications in physics and engineering.