Why a Fridge Magnet Can Hold On for Years Without Using Any Energy

Why does a fridge magnet hold a sheet of paper for years without using any energy? In 1907 Pierre Weiss proposed a hidden field inside iron so strong that no laboratory magnet of his time came close to it. This calm lecture follows the thin, rubbery magnet on a refrigerator door, from the north and south stripes on its hidden face to the electrons that line up inside its ferrite grains. The sources it rests on include Nature volume 119, page 353 from 1927, Zeitschrift für Physik volume 49, pages 619 to 636 from 1928, OpenStax University Physics section 7.1, and Mahmood and Bsoul in 2017. It also explains why holding something still does no work, and where the one real payment is made. 📖 Stay with the sheet of paper under the magnet, and learn why holding costs nothing while the energy spent on the leap to the door is paid back only when the magnet is pulled away. 👉 Subscribe to The Unhurried Universe and return on a quiet night for the next lecture. 0:00 A Sheet of Paper on the Refrigerator Door 9:36 The Enormous Field Inside Iron 22:26 Why Holding Something Costs Nothing 34:38 The Quiet Agreement Between Electrons 47:51 From the Stripes to the Grains 1:01:02 But Surely Something Must Be Paying 1:13:49 The Humble Magnet That Still Does the Work 1:26:43 The Things That Hold Us Up All Night 1:37:35 What We Still Do Not Know About Magnets 1:50:34 The Paper Is Still There #TheUnhurriedUniverse #FridgeMagnet #Magnetism #Physics #Ferrite #Electrons #Ferromagnetism #Science #MagneticField #PierreWeiss #Documentary #ScienceExplained