{"product_id":"jumpring-thomson-jumping-ring","title":"Jumpring – Thomson’s Jumping Ring Physics Sticker","description":"\u003cp\u003eJumpring, a young armoured knight, watches a glowing ring hover above an iron-cored coil.\u003c\/p\u003e\u003ch3\u003eThe Physics\u003c\/h3\u003e\u003cp\u003eIn 1887 Elihu Thomson showed that a metal ring slipped over the iron core of a coil leaps into the air when AC is switched on. The changing flux induces a current in the ring; by Lenz's law it opposes the change, and because the ring current lags behind, the net force on average pushes the ring away. With steady AC a ring can float.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eF ∝ −I\u003csub\u003ecoil\u003c\/sub\u003e I\u003csub\u003ering\u003c\/sub\u003e\u003c\/strong\u003e\u003c\/p\u003e\u003cul\u003e\n\u003cli\u003eI\u003csub\u003ecoil\u003c\/sub\u003e: current in the coil (A)\u003c\/li\u003e\n\u003cli\u003eI\u003csub\u003ering\u003c\/sub\u003e: induced current in the ring (A)\u003c\/li\u003e\n\u003c\/ul\u003e\u003cp\u003eCut the ring and nothing happens: no closed path, no current. Cool it in liquid nitrogen and it flies higher, as its resistance drops.\u003c\/p\u003e\u003cp\u003e\u003cem\u003eHonest caveat:\u003c\/em\u003e The repulsion relies on the phase lag from the ring's inductance; a purely resistive ring would feel no average force.\u003c\/p\u003e\u003ch3\u003eOn the sticker\u003c\/h3\u003e\u003cp\u003eJumpring holds his hand by a cyan ring of light floating above a glowing coil. Printed text: \u003cstrong\u003eJUMPRING\u003c\/strong\u003e. Pixel-art kiss-cut vinyl sticker, white, in 2″, 3″, 4″ and 6″ sizes.\u003c\/p\u003e","brand":"Printify","offers":[{"title":"2\" × 2\" \/ White","offer_id":50964270514279,"sku":"81581501766262016022","price":4.99,"currency_code":"USD","in_stock":true},{"title":"3\" × 3\" \/ White","offer_id":50964270547047,"sku":"24730313190792222390","price":6.99,"currency_code":"USD","in_stock":true},{"title":"4\" × 4\" \/ White","offer_id":50964270579815,"sku":"20520005148408263904","price":8.99,"currency_code":"USD","in_stock":true},{"title":"6\" × 6\" \/ White","offer_id":50964270612583,"sku":"63709240958966394025","price":11.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0596\/8746\/9159\/files\/6121390519915257513_1200.jpg?v=1793664083","url":"https:\/\/pixelatedphysics.com\/hi\/products\/jumpring-thomson-jumping-ring","provider":"Pixelated Physics","version":"1.0","type":"link"}