At the Palais de la Decouverte in Paris, they showed me this experiment where a 1kg aluminium plate is levitated above a large coil of wire that is being supplied with 800A of alternating current at 900Hz. This is by far the best demonstration of electromagnetic induction I have ever seen. Back in London, I visited the magnetic lab of Michael Faraday in the basement of the Royal Institution. It was here that he did his groundbreaking work on induction. People had previously observed that current in a wire causes a compass needle to deflect, but more exciting was the prospect of using a magnetic field to generate current. Faraday created his famous induction ring by winding two coils of insulated wire onto an iron ring. When he connected a battery to one coil, a small pulse of current was induced in the other. When the battery was disconnected, current was induced in the other direction. This led Faraday to the conclusion that current was induced in the second coil only when the magnetic field through it was changing. And if they hadn't been wrapped on the same ring, Faraday may have noticed that the two coils repel each other when the current is induced due to the interaction of their magnetic fields. This is the same thing that is happening with the aluminium plate, except we're using alternating current to create a continually changing magnetic field. This induces an alternating current in the plate, producing an opposing magnetic field which levitates the disk.

How to lead a happier and longer life. Check out our sponsor: https://betterhelp.com/veritasium to get matched with a professional therapist who will listen and help. ▀▀▀ A huge thanks to Prof. Robert Waldinger for all his help with this video. To learn more about what makes for a good life, visit: https://the-good-life-book.com/ and https://www.youtube.com/watch?v=8KkKuTCFvzI&pp=ygUJd2FsZGluZ2Vy A special thanks to Prof. Julianne Holt-Lunstad for her expert advice on the importance of social connections and the detrimental effects of loneliness and social isolation. ▀▀▀ Additional Videos: Family Reacts to Winning CA$1 Million Lotto, NowThisNews via YouTube - https://ve42.co/CA1Lottery Woman claims to be $1 billion Powerball winner, KTLA 5 via YouTube - https://ve42.co/1BilLottery Old Lottery Winner Meets Young Lottery Winner | The Gap, LADbible TV via YouTube - https://ve42.co/LADBibleLottery Why eyewitnesses get it wrong - Scott Fraser, TED-Ed via Youtube - https://ve42.co/TEDFraser Surgeon General discusses health risks of loneliness and steps to help connect with others, PBS NewsHour via YouTube - https://ve42.co/PBS-SG ▀▀▀ References: Waldinger, R., & Schulz, M. (2023). The Good Life: Lessons from the World's Longest Scientific Study of Happiness. Simon and Schuster. Lindqvist et al. (2020). Long-run effects of lottery wealth on psychological well-being. The Review of Economic Studies. - https://ve42.co/Lindqvist2020 Wen et al. (2011). Minimum amount of physical activity for reduced mortality and extended life expectancy: a prospective cohort study. The lancet. - https://ve42.co/Wen2011 Nocon et al. (2008). Association of physical activity with all-cause and cardiovascular mortality: a systematic review and meta-analysis. European Journal of Preventive Cardiology. - https://ve42.co/Nocon2008 Blondell et al. (2014). Does physical activity prevent cognitive decline and dementia?: A systematic review and meta-analysis of longitudinal studies. BMC public health. - https://ve42.co/Blondell2014 Office of the Surgeon General. (2023). Our Epidemic of Loneliness and Isolation: The US Surgeon General’s Advisory on the Healing Effects of Social Connection and Community. - https://ve42.co/LonelinessEpidemic Holt-Lunstad et al. (2010). Social relationships and mortality risk: a meta-analytic review. PLoS medicine. - https://ve42.co/Holt-Lunstad2010 Valtorta et al. (2016). Loneliness and social isolation as risk factors for coronary heart disease and stroke: systematic review and meta-analysis of longitudinal observational studies. Heart. - https://ve42.co/Valtorta2016 Shovestul et al. (2020). Risk factors for loneliness: The high relative importance of age versus other factors. PloS one. - https://ve42.co/Shovestul2020 Donovan et al. (2017). Loneliness, depression and cognitive function in older US adults. International journal of geriatric psychiatry. - https://ve42.co/Donovan2017 Lara et al. (2019). Does loneliness contribute to mild cognitive impairment and dementia? A systematic review and meta-analysis of longitudinal studies. Ageing research reviews. - https://ve42.co/Lara2019 Holt-Lunstad et al. (2015). Loneliness and social isolation as risk factors for mortality: a meta-analytic review. Perspectives on psychological science. - https://ve42.co/Holt-Lunstad2015 McIntyre et al. (2015). Compulsive Internet use and relations between social connectedness, and introversion. Computers in Human Behavior. - https://ve42.co/McIntyre2015 Kahneman & Deaton. (2010). High income improves evaluation of life but not emotional well-being. Proceedings of the national academy of sciences. - https://ve42.co/Kahneman2010 Killingsworth. (2021). Experienced well-being rises with income, even above $75,000 per year. Proceedings of the National Academy of Sciences. - https://ve42.co/Killingsworth2021 Killingsworth et al. (2023). Income and emotional well-being: A conflict resolved. Proceedings of the National Academy of Sciences. - https://ve42.co/Killingsworth2023 ▀▀▀ Special thanks to our Patreon supporters: Adam Foreman, Anton Ragin, Balkrishna Heroor, Bernard McGee, Bill Linder, Burt Humburg, Chris Harper, Dave Kircher, Diffbot, Evgeny Skvortsov, Gnare, John H. Austin, Jr., john kiehl, Josh Hibschman, Juan Benet, KeyWestr, Lee Redden, Marinus Kuivenhoven, Max Paladino, Meekay, meg noah, Michael Krugman, Orlando Bassotto, Paul Peijzel, Richard Sundvall, Sam Lutfi, Stephen Wilcox, Tj Steyn, TTST, Ubiquity Ventures ▀▀▀ Directed by Casper Mebius Written by Casper Mebius, Petr Lebedev, and Derek Muller Edited by Peter Nelson Animated by Fabio Albertelli and Ivy Tello Filmed by Derek Muller, Emily Zhang, and Zyan Treadwell Produced by Casper Mebius, Petr Lebedev, Han Evans, and Derek Muller Additional video/photos supplied by Getty Images and Storyblocks Music from Epidemic Sound Thumbnail by Ren Hurley ... https://www.youtube.com/watch?v=vSQjk9jKarg

A basketball and a 5kg medicine ball are dropped simultaneously. Which one hits the ground first? It seems obvious that the heavy one should accelerate at a greater rate and therefore land first because the force pulling it down is greater. But this is forgetting inertia - the tendency of mass to resist changes in motion. Therefore, although the force on the medicine ball is greater, it takes this larger force to accelerate the ball at the same rate as the basketball.

How do our eyes scan across a landscape? Contrary to popular belief, they don't scan smoothly across a scene, they observe a series of images. The eye is capable of panning smoothly however. If something moves in your field of view, your eyes track it smoothly. This has an important effect on our perception of motion. It makes it more difficult to see when objects are accelerating since the eye tracks all motion quite smoothly.