Point P is situated at the mid-point of the line joining the centres of the circular wires which have same radii (R). The magnetic fields (B) at P due to the currents in the wires are in same direction. Magnitude of magnetic field at point, P B=2{2(R2+4R2)3/2μ0NIR2} =853/2μ0NIR2=53/2R8μ0NI
A Helmholtz coil has 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…
JEE Main 2018 — Physics Electromagnetism
A Helmholtz coil has 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 magnetic field at P, midway between the centres A and C, is given by (Refer to figure): 
Held on 15 Apr 2018 · Verified 6 Jul 2026.
Options
- A
53/2R4Nμ0I
- B
53/2R8Nμ0I
- C
51/2R4Nμ0I
- D
51/2R8Nμ0I
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