Encyclopedia Magnetica™

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Magnetic field strength H at the centre of a Helmholtz coil
$$ H_{centre}(t) = \frac{N_{each}·I (t)· 8 } {r·\sqrt{125}} \approx 0.71554·\frac{N_{each}·I}{r} $$	(A/m)
where: $I(t)$ - current (A) at time $t$ (s), $N_{each}$ - number of turns (unitless) of each half-coil, $r$ - radius (m)

Current I = Radius r = Choose option: Number of turns N = (unitless) H = B (μ₀) =
Notes: This equation is valid only for infinitely “thin” coils. The instantaneous values of H are directly proportional to the instantaneous values of I. The value of B(μ₀) is for vacuum (i.e. non-magnetic medium).