
The magnetic field due to the rectangular loop at its centre is:
B=4×4π(2L)μ0i[21+21]=πL22μ0i
Therefore, the flux through the circular loop ϕ=πR2×B=L22μ0R2i
If M is the mutual inductance, then
Mdtdi=dtdϕ=L22μ0R2dtdi
⇒M=L22μ0R2
JEE Main 2023 — Physics Electromagnetism
Find the mutual inductance in the arrangement, when a small circular loop of wire of radius R is placed inside a large square loop of wire of side L(L≫R). The loops are coplanar and their centres coincide :

Held on 29 Jan 2023 · Verified 6 Jul 2026.
M=L2μ0R2
M=L222μ0R
M=L22μ0R2
M=L22μ0R
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