Final answer:
To determine the magnetic flux through a square loop, calculate the induced emf, determine the direction of the induced current, analyze how the emf varies in time, and calculate the force required to pull the loop away from the line of current.
Step-by-step explanation:
To determine the magnetic flux through a square loop of side a when one side is parallel to and a distance b from a straight wire carrying current I, we can use Ampère's law.
Assuming the loop is pulled away from the wire at speed v, the induced emf can be calculated using Faraday's law of electromagnetic induction.
The direction of the induced current can be determined using Lenz's law, which states that the induced current always opposes the change in magnetic flux.
The emf's variation in time can be determined by considering the position and velocity of the loop sides.
The force required to pull the loop away from the line of current can be calculated using the formula for the magnetic force on a current-carrying wire.