{"product_id":"fizeaus-toothed-wheel-plate-023-physics-poster","title":"Fizeau's Toothed Wheel – Plate 023 Physics Poster","description":"\u003cp\u003ePlate 23 speaks for itself: \u003cem\u003e“Seven hundred twenty teeth, and light was caught.”\u003c\/em\u003e\u003c\/p\u003e\u003ch3\u003eThe Physics\u003c\/h3\u003e\u003cp\u003eFizeau sent light through the gaps of a spinning toothed wheel to a mirror 8.6 km away. At the right spin rate the returning light hit a tooth and the image went dark, timing the round trip.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003ec = 4 d N f\u003c\/strong\u003e\u003c\/p\u003e\u003cul\u003e\n\u003cli\u003ec: speed of light, m s⁻¹\u003c\/li\u003e\n\u003cli\u003ed: wheel-to-mirror distance, m\u003c\/li\u003e\n\u003cli\u003eN: number of teeth, dimensionless\u003c\/li\u003e\n\u003cli\u003ef: rotation rate at first eclipse, rev s⁻¹\u003c\/li\u003e\n\u003c\/ul\u003e\u003cp\u003e720 teeth, 8633 m, 12.6 rev\/s. Fizeau, 1849: about 315 000 km\/s.\u003c\/p\u003e\u003cp\u003e\u003cem\u003eHonest caveat:\u003c\/em\u003e Plugging the rounded 12.6 rev\/s into the formula gives about 313 000 km\/s; Fizeau's published value was about 315 000 km\/s, roughly 5% above today's exact 299 792.458 km\/s.\u003c\/p\u003e\u003ch3\u003eSources\u003c\/h3\u003e\u003cul\u003e\u003cli\u003eH. Fizeau, C. R. Acad. Sci. 29, 90 (1849).\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eOn the poster\u003c\/h3\u003e\u003cp\u003ePlate 023, “Fizeau's Toothed Wheel”: the pixel-art plate with its slogan “Seven hundred twenty teeth, and light was caught.”, the key equation and the facts panel shown above. Pixelated Physics. Physics. Personified.\u003c\/p\u003e","brand":"Printify","offers":[{"title":"9'' x 12\" (Vertical) \/ Matte","offer_id":50961815502951,"sku":"33115046531533417201","price":19.99,"currency_code":"USD","in_stock":true},{"title":"9'' x 12\" (Vertical) \/ Fine Art","offer_id":50961815535719,"sku":"36610622371326326599","price":29.99,"currency_code":"USD","in_stock":true},{"title":"9'' x 12\" (Vertical) \/ Semi Glossy","offer_id":50961815568487,"sku":"95685680683637021333","price":19.99,"currency_code":"USD","in_stock":true},{"title":"18″ x 24″ (Vertical) \/ Fine Art","offer_id":50961815601255,"sku":"13476576304597920469","price":44.99,"currency_code":"USD","in_stock":true},{"title":"18″ x 24″ (Vertical) \/ Semi Glossy","offer_id":50961815634023,"sku":"10808418898644560962","price":29.99,"currency_code":"USD","in_stock":true},{"title":"18″ x 24″ (Vertical) \/ Matte","offer_id":50961815666791,"sku":"33448091574620232248","price":29.99,"currency_code":"USD","in_stock":true},{"title":"36'' x 48\" (Vertical) \/ Matte","offer_id":50961815699559,"sku":"33944570313457725997","price":69.99,"currency_code":"USD","in_stock":true},{"title":"36'' x 48\" (Vertical) \/ Fine Art","offer_id":50961815732327,"sku":"11818503626937484619","price":119.99,"currency_code":"USD","in_stock":true},{"title":"36'' x 48\" (Vertical) \/ Semi Glossy","offer_id":50961815765095,"sku":"23836485187110859039","price":69.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0596\/8746\/9159\/files\/18426811134014814416_2048.jpg?v=1793633360","url":"https:\/\/pixelatedphysics.com\/tr\/products\/fizeaus-toothed-wheel-plate-023-physics-poster","provider":"Pixelated Physics","version":"1.0","type":"link"}