{"product_id":"displacera-displacement-current","title":"Displacera – Maxwell’s Displacement Current \/ J = ε0 ∂E\/∂t Physics Sticker","description":"\u003cp\u003eDisplacera, a hooded field-weaver, holds a glowing disc of light between his hands.\u003c\/p\u003e\u003ch3\u003eThe Physics\u003c\/h3\u003e\u003cp\u003eAmpère's law broke down at a charging capacitor: current flows in the wire but not across the gap. James Clerk Maxwell fixed it in 1861–65 by adding a term for the changing electric field in the gap, which makes a magnetic field just as a real current does (“A Dynamical Theory of the Electromagnetic Field”, Phil. Trans. 155, 459, 1865). With it, the equations predicted electromagnetic waves travelling at the speed of light.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eJ\u003csub\u003ed\u003c\/sub\u003e = ε\u003csub\u003e0\u003c\/sub\u003e ∂E\/∂t\u003c\/strong\u003e\u003c\/p\u003e\u003cul\u003e\n\u003cli\u003eJ\u003csub\u003ed\u003c\/sub\u003e: displacement current density (A\/m²)\u003c\/li\u003e\n\u003cli\u003eε\u003csub\u003e0\u003c\/sub\u003e: permittivity of free space (F\/m)\u003c\/li\u003e\n\u003cli\u003e∂E\/∂t: rate of change of the electric field (V m⁻¹ s⁻¹)\u003c\/li\u003e\n\u003c\/ul\u003e\u003cp\u003eLight itself is changing electric and magnetic fields keeping each other going through this term. Hertz confirmed the waves in 1887–88.\u003c\/p\u003e\u003cp\u003e\u003cem\u003eHonest caveat:\u003c\/em\u003e No charge actually crosses the gap; the name is a leftover from Maxwell's mechanical model.\u003c\/p\u003e\u003ch3\u003eOn the sticker\u003c\/h3\u003e\u003cp\u003eDisplacera cups a glowing cyan disc of light between his hands. Printed text: \u003cstrong\u003eDISPLACERA\u003c\/strong\u003e with the line \u003cstrong\u003eJ = ε0 ∂E\/∂t\u003c\/strong\u003e. Pixel-art kiss-cut vinyl sticker, white, in 2″, 3″, 4″ and 6″ sizes.\u003c\/p\u003e","brand":"Pixelated Physics","offers":[{"title":"2\" × 2\" \/ White","offer_id":50964269367399,"sku":"79006534210150789072","price":4.99,"currency_code":"USD","in_stock":true},{"title":"3\" × 3\" \/ White","offer_id":50964269400167,"sku":"28359199971580092171","price":6.99,"currency_code":"USD","in_stock":true},{"title":"4\" × 4\" \/ White","offer_id":50964269432935,"sku":"12143697542034297150","price":8.99,"currency_code":"USD","in_stock":true},{"title":"6\" × 6\" \/ White","offer_id":50964269465703,"sku":"10466967660327250083","price":11.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0596\/8746\/9159\/files\/1676204676302991162_1200.jpg?v=1793663883","url":"https:\/\/pixelatedphysics.com\/ko\/products\/displacera-displacement-current","provider":"Pixelated Physics","version":"1.0","type":"link"}