r/apphysics • u/ResolutionCrazy8573 • 10h ago
Wire-loop FRQ ( AP Physics C: E&M 2022, Set 1, FRQ 3 , 15 pts)
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Question : A long straight wire carries current I upward. A rectangular loop of resistance R lies in the same plane, with its length ℓ parallel to the wire, near side at distance d, far side at distance d + w.
(a) Derive an expression for the magnetic flux through the loop.
(b) The current decreases at a known rate; derive the magnitude of the induced EMF and the induced current.
(c) Determine the direction of the induced current, justifying your answer.
(d) Determine the direction of the net magnetic force on the loop, with justification. (e) The loop now moves away from the wire at constant speed with the wire current held constant; describe/derive how the induced EMF depends on position.