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Re: [Phys-L] Helmholtz coils




On 2017/Jun/08, at 14:46, John Denker via Phys-l <phys-l@mail.phys-l.org <mailto:phys-l@mail.phys-l.org>> wrote:


Now, when we use /two/ coils, symmetrically arranged about the
origin, the first-order term must vanish by symmetry. Forsooth,
all of the odd-order terms must vanish. The function, whatever
it is, must be an even function ... assuming the engineering was
done properly.

The zeroth order term survives. It is the term we wanted all along.


At one time I understood why push-pull amps. cancelled even order harmonics.

My intuition: it’s similar to JD’s argument(s).

Speaking of Helmholtz, There’s a pic of an e-magnet surrounding a Wilson CC. “The coils are curved, unlike the usual Helmholtz coils, and permit a uniform field to be obtained.” Leprince-Ringuet "Cosmic Rays" p. 102 plate 7.5. [Includes a glowing forward by John A. Wheeler. 1950]

This is (was) in the Chamonix lab at 3650 m. (L-R built during the war) ref: Nageotten. Compt. Rend. acad. sci. Paris, 220, 557, 1945

bc, now deaf no longer a HIFi aficionado.