
As length of both the wires is same, 2πR=4a
⇒Ra=42π
⇒Ra=2π

BA=2Rμ0i and
BB=πaμ0i(22)
Therefore, ratio will be BBBA=2Rμ0i×22μ0iπa
=42Rπa=42π(2π)=82π2
JEE Main 2016 — Physics Electromagnetism
Two identical wires A and B, each of length l, carry the same current I . Wire A is bent into a circle of radius R and wire B is bent to form a square of side a. If BA and BB are the values of magnetic field at the centres of the circle and square respectively, then the ratio BBBA is
Held on 3 Apr 2016 · Verified 6 Jul 2026.
16π2
82π2
8π2
162π2
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