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Magnetonix

Bohr Magneton / The Unit of Atomic Magnetism Physics

$4.99 USD
$4.99 USD
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Magnetonix, a compass-needle imp of The SI Guard, is ringed by his own electron loop and is a magnet of about one Bohr magneton.

The Physics

An electron with one unit of orbital angular momentum ħ has a magnetic moment of one Bohr magneton. This is the natural unit for atomic and electron magnetism.

μB = eħ/(2me) = 9.274 010 0657(29) × 10⁻²⁴ J/T

  • μB: Bohr magneton (J/T)
  • e: elementary charge (exact)
  • ħ: reduced Planck constant (exact)
  • me: electron mass (measured)

Value: CODATA 2022 (NIST). μB is not exact in the 2019 SI because me is measured. Because the electron is negative, its moment points opposite to its angular momentum. The electron's spin moment is about 1.001 16 μB (|ge|/2), and the extra 0.1% comes from quantum electrodynamics.

Honest caveat: Spin is intrinsic. The electron is not a tiny spinning ball of charge: a classical sphere would need a surface speed faster than light to give this moment.

On the sticker

Magnetonix stands inside his glowing electron orbit, under a magnetic-field-line aurora. Printed text: MAGNETONIX with the line μB = eħ/(2me). Pixel-art kiss-cut vinyl sticker, white, in 2″, 3″, 4″ and 6″ sizes.

Shipping calculated at checkout by destinationMade to order, ships in 2–5 business days

Details

Size3″ × 3″

3″ × 3″ kiss-cut sticker.

Shipping

Shipping calculated at checkout by destination. Printed to order for you.

Delivery times & where we ship

Returns & replacements21 days

Every item is printed to order, so we can’t accept returns or exchanges for change of mind, or if you ordered the wrong size or colour.

Print defect, misprint, damage or the wrong item? We’ll send a free replacement, or a refund if you prefer. Report it within 21 days of delivery with a photo; no need to send it back.

Full refund & replacement policy

Field notes

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