The magnetic field produced by a current-carrying straight wire decreases as the distance from the wire increases, as illustrated by the concentric circles becoming larger in the figure.

When the compass is moved away from the copper wire while maintaining the same current, the deflection in the needle decreases.

An increase in current results in an increase in the magnitude of the magnetic field produced at a given point.

The deflection of the compass needle increases as the current in the copper wire is increased.

Magnetic field lines do not cross each other because, at the point of intersection, the compass needle would have to point towards two directions simultaneously, which is not possible.