{"product_id":"ayrtha-pixel-hoodie","title":"Ayrtha – Hertha Ayrton, the Electric Arc and Sand Ripples Pixel Hoodie","description":"\u003cp\u003eAyrtha is a respectful pixel portrait of Hertha Ayrton, after a Bain News Service photograph of about 1900, holding a white-violet carbon arc above a basin of sand ripples.\u003c\/p\u003e\u003ch3\u003eThe Physics\u003c\/h3\u003e\u003cp\u003eHertha Ayrton (1854–1923) showed that the hissing and instability of carbon arc lamps came from oxygen reaching the hot crater of the positive carbon, and summed up her arc work in \u003cem\u003eThe Electric Arc\u003c\/em\u003e (1902). There she gave an empirical law for the voltage across an arc, now called the Ayrton equation. Her ripple paper on how vortices build sand ripple marks, “The origin and growth of ripple-mark”, was read before the Royal Society on 16 June 1904. In 1906 she became the first woman to receive the Society’s Hughes Medal.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eV = a + b l + (c + d l) \/ I\u003c\/strong\u003e\u003c\/p\u003e\u003cul\u003e\n\u003cli\u003eV: voltage across the arc (V)\u003c\/li\u003e\n\u003cli\u003eI: arc current (A)\u003c\/li\u003e\n\u003cli\u003el: arc length, the gap between the carbons (m)\u003c\/li\u003e\n\u003cli\u003ea, b, c, d: empirical constants fitted for given electrodes (units V, V m⁻¹, W, W m⁻¹)\u003c\/li\u003e\n\u003c\/ul\u003e\u003cp\u003eThe (c + d l)\/I term makes V fall as I rises, a negative differential resistance, which is why an arc needs a series resistor to stay stable. Sources: H. Ayrton, \u003cem\u003eThe Electric Arc\u003c\/em\u003e (1902); \u003cem\u003eProc. R. Soc. Lond.\u003c\/em\u003e 74, 565 (1904), doi:10.1098\/rspl.1904.0159, and full paper \u003cem\u003eProc. R. Soc. A\u003c\/em\u003e 84, 285 (1910), doi:10.1098\/rspa.1910.0076; MacTutor, “Hertha Marks Ayrton”; English Heritage blue plaque.\u003c\/p\u003e\u003cp\u003e\u003cem\u003eHonest caveat:\u003c\/em\u003e The Ayrton equation is empirical, fitted to carbon arcs; it is not derived from plasma physics and does not hold for every arc. How sand ripples grow and choose their spacing is still studied.\u003c\/p\u003e\u003ch3\u003eIn character\u003c\/h3\u003e\u003cp\u003e\u003cem\u003eThey said the arc hissed because it was fickle. It hissed because it was breathing oxygen. I listened until it told me why.\u003c\/em\u003e\u003c\/p\u003e\u003ch3\u003eOn the hoodie\u003c\/h3\u003e\u003cp\u003eFront: a tiny arc between two rods over three ripples. Back: a pixel portrait of Hertha Ayrton with “CROWNED IN HER OWN LIGHT” and “HERTHA AYRTON - 1906”. Gildan 18500 Heavy Blend hoodie, Black, S to 5XL.\u003c\/p\u003e\u003cp\u003ePart of the \u003cstrong\u003eUnsung Hands\u003c\/strong\u003e set with \u003ca href=\"\/sv\/products\/sponara-pixel-hoodie\"\u003eSponara\u003c\/a\u003e, \u003ca href=\"\/sv\/products\/recoilwyn-pixel-hoodie\"\u003eRecoilwyn\u003c\/a\u003e. Browse all \u003ca href=\"\/sv\/collections\/hoodies\"\u003ephysics hoodies\u003c\/a\u003e, more \u003ca href=\"\/sv\/collections\/electromagnetism\"\u003eelectromagnetism designs\u003c\/a\u003e, or the \u003ca href=\"\/sv\/collections\/deep-cuts\"\u003eDeep Cuts\u003c\/a\u003e.\u003c\/p\u003e","brand":"Pixelated Physics","offers":[{"title":"Black \/ S","offer_id":50964470005863,"sku":"10012611444486418513","price":64.99,"currency_code":"USD","in_stock":true},{"title":"Black \/ M","offer_id":50964470038631,"sku":"17536997199752288188","price":64.99,"currency_code":"USD","in_stock":true},{"title":"Black \/ L","offer_id":50964470071399,"sku":"35361978633547981427","price":64.99,"currency_code":"USD","in_stock":true},{"title":"Black \/ XL","offer_id":50964470104167,"sku":"30667800467075846342","price":64.99,"currency_code":"USD","in_stock":true},{"title":"Black \/ 2XL","offer_id":50964470136935,"sku":"15658650901028805190","price":64.99,"currency_code":"USD","in_stock":true},{"title":"Black \/ 3XL","offer_id":50964470169703,"sku":"20426556088540888526","price":64.99,"currency_code":"USD","in_stock":true},{"title":"Black \/ 4XL","offer_id":50964470202471,"sku":"19461674590263711571","price":64.99,"currency_code":"USD","in_stock":true},{"title":"Black \/ 5XL","offer_id":50964470235239,"sku":"10402213787029082724","price":64.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0596\/8746\/9159\/files\/03_H15_4f43f7cb-cfac-4d6e-af1a-f76a730e0d82.png?v=1793678497","url":"https:\/\/pixelatedphysics.com\/sv\/products\/ayrtha-pixel-hoodie","provider":"Pixelated Physics","version":"1.0","type":"link"}