Physics
Physics
Problem
Two identical coaxial circular coils X and Y, each of radius , carry the same current of . When viewed from the same side, the current in X is clockwise whereas in Y it is anticlockwise. What is the resultant magnetic field at the midpoint on the common axis of the two coils? a) Directed along the axis towards the observer. b) Zero, the magnetic fields cancel out. c) Directed along the axis away from the observer. d) Along a tangent to the coils.Intuitive explanation
The key insight is recognizing that opposite current directions create opposite magnetic field directions along the axis. Since the coils are identical and equidistant from the midpoint, their individual field magnitudes are equal—but they point in opposite directions. When you add two equal-magnitude vectors pointing opposite ways, they cancel completely, giving zero net field at the center.
Intuitive explanation
The key insight is recognizing that opposite current directions create opposite magnetic field directions along the axis. Since the coils are identical and equidistant from the midpoint, their individual field magnitudes are equal—but they point in opposite directions. When you add two equal-magnitude vectors pointing opposite ways, they cancel completely, giving zero net field at the center.