Final answer:
In physics, parallel current-carrying wires exert magnetic forces upon on each other. Wires carrying currents in the same direction attract, while wires carrying currents in opposite directions repel. In a triangle of wires with one opposite current, two sides experience attraction.
Step-by-step explanation:
The subject of this question involves the magnetic force between current-carrying wires. In physics, the interaction between two parallel current-carrying wires depends on the direction of the currents. If currents are in the same direction, they attract each other; if they flow in opposite directions, they repel each other. This is due to the magnetic fields they generate, which interact according to the right-hand rule (RHR).
In the specific case presented by the student where three wires form an equilateral triangle and one current is opposite the other two, imagine a triangle with corners A, B, and C. If wire A has a current opposite to wires B and C, according to RHR-1, wire A will be attracted to both B and C, and wires B and C will also be attracted to each other because the currents are in the same direction. This indicates that two sides of the triangle involve attraction, and one side may involve repulsion or attraction depending on the relative orientation of the currents.