A coaxial wire consists of a copper wire of radius 1 mm surrounded by a copper sheath of inside radius 1.5 mm and an outside radius 2 mm.A 3-A current flows in one direction down the core and in the opposite direction down the sheath.What is the magnitude of the magnetic field at a radius of 3 mm from the center of the wire?
A)0 T
B)1.25 µT
C)3.15 µT
D)4.20 µT
E)5.15 µT

Question

Quizplus · Accepted Answer

The magnetic field at a radius of 3 mm from the center of the wire, which is outside both the core and the sheath, is 0 T due to the principle of superposition. The magnetic fields generated by the currents in the core and the sheath cancel each other out at this point, as they flow in opposite directions.

A Coaxial Wire Consists of a Copper Wire of Radius