A student attempts to draw the combined magnetic field in the vicinity of two long
PHYSICS · Multi-part · AP · Physics 2: Algebra-based · Magnetism and Electromagnetism · Magnetism and Electromagnetism
Problem
A student attempts to draw the combined magnetic field in the vicinity of two long, straight conductors that cross each other at right angles but do not touch. One conductor lies along the x-axis and carries a current toward +x. The other lies along the y-axis and carries a current toward +y. The student’s sketch shows semicircular field lines centered on the intersection point, suggesting that the fields merge into continuous arcs. You are asked to critique and correct the student’s representation.
(1) Part 1: Identify and explain two specific errors in the student’s depiction of the magnetic field.
(2) Part 2: Provide a corrected qualitative description of the magnetic field pattern in the region near the intersection. In words, describe the field direction in each quadrant around the intersection point.
(3) Part 3: A small square loop of wire, lying in the plane z=0 and centered at the intersection, carries a current that circulates clockwise when viewed from z>0. Using your corrected field description, determine qualitatively the net force and net torque (if any) acting on the loop. Justify your conclusions.