Magnetic field at point P, due to both coils, Bp=2[2(R2+4R2)3/2μ0NIR2]=853/2R3μ0NIR2=53/2R8Nμ0I.
JEE Main 2018 — Physics Electromagnetism
A Helmholtz coil has a pair of loops, each with N turns and radius R. They are placed coaxially at distance R and the same current I flows through the loops in the same direction. The magnitude of the magnetic field at P, midway between the centres A and C, is given by [Refer to figure given below]:

Held on 15 Apr 2018 · Verified 6 Jul 2026.
51/2R8Nμ0I
53/2R4Nμ0I
51/2R4Nμ0I
53/2R8Nμ0I
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