Based on the elements mentioned (compass, wire carrying current, and magnetic field), the particles are demonstrating the magnetic field generated by the current flowing through the wire. The compass is used to visualize the direction of the magnetic field created by the electric current in the wire. When current flows through a wire, it produces a magnetic field around it, which can be detected by the compass.
If you're looking for the broader concept that encompasses these elements, you might also consider that they relate to the principles of an electromagnetic field, which combines both electric and magnetic fields, but in the context given, the most direct answer is the magnetic field.
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