A loop bent in the shape below carries a conventional current in the direction marked. What is the magnitude $|\vec{B}|$ of the magnetic field at the point $a$ on the diagram
-(a) due to just the horizontal segments of the loop?
A) $\mu_{0} / / 4 \pi R$
B) $\mu_{0} / / 4 R$
C) $\mu_{0} / / 8 R$
D) $\mu_{0} / / 2 R$
E) $\mu_{0} / / R$
F) Zero

Question

Quizplus · Accepted Answer

The magnetic field due to the horizontal segments of the loop at point $a$ is zero because the magnetic fields from the two horizontal segments cancel each other out. Each segment generates a magnetic field at point $a$ that is equal in magnitude but opposite in direction, leading to a net magnetic field of zero.

A Loop Bent in the Shape Below Carries a Conventional ∣B⃗∣|\vec{B}|∣B∣

A Loop Bent in the Shape Below Carries a Conventional $|\vec{B}|$