Final answer:
A square loop carrying current has a tendency to expand or contract based on the direction of the current relative to the magnetic field.
Step-by-step explanation:
In a uniform magnetic field, a current-carrying loop, such as a square loop, experiences forces and torques. The magnetic force on a straight current-carrying wire is given by I x B, where I is the current and B is the magnetic field.
For a square loop carrying current, the side of the loop experiences a magnetic force that is perpendicular to both the current direction and the magnetic field direction. This force depends on the magnitude and direction of the current.
If the current in the loop is in the same direction as the magnetic field, the forces on each side of the loop will be in the same direction, causing the loop to contract. If the current is in the opposite direction, the forces will be in opposite directions, causing the loop to expand.