Two concentric circular wire loops in the same plane each carry a current.The larger loop as a current of 8.46 A circulating clockwise and has a radius of 6.20 cm.The smaller loop has a radius of 4.42 cm.What is the magnitude and direction of the current in the smaller loop if the total magnetic field at the center of the system is zero?
A) 6.03 A CCW
B) 6.03 A CW
C) 12.8 A CCW
D) 12.8 A CW

Question

Quizplus · Accepted Answer

The magnetic field at the center due to a current-carrying loop is proportional to the current and inversely proportional to the radius. To cancel the field from the larger loop, the smaller loop must have a current in the opposite direction (CCW) and a magnitude such that the product of current and radius is the same for both loops. Solving gives 6.03 A CCW.

Two Concentric Circular Wire Loops in the Same Plane Each