The Pondering Physics Teacher

A magnet is released at the top. Why does it drop so quickly initially but slows down at the lower portion? The video below shows what happens between the two lower plates in slow motion.

Even IKEA is selling a device that utilises EMI. No more power banks? No more messy wires? Image from Digital Trends (https://www.digitaltrends.com/mobile/best-wireless-chargers/) How does it work?

I initially thought that even with a different amplitude two waves will still form a standing wave if they have the same frequency and move in opposite directions. So I tested it using Mr Loo Wee Kang's simulation and it turned out I was wrong. The blue and green waves are the individual waves moving in opposite directions. The red is vector sum of the two waves. As observed from the video, the red wave is not a standing wave but propagates.

http://www.physics.usyd.edu.au/teach_res/mp/doc/em_emf.htm While looking at the simulation, follow the graph plotted as the magnet moves through the solenoid. Lenz's law agrees with the conservation of energy by resisting the change that causes it. Mechanical energy changes to electrical energy and in turn thermal energy due to the resistance of the wires. Current flows from low to high potential in this case. Remember it is EMF (electromotive force) we are looking at here so in the same way IN a cell/battery current flows from low to high potential. What if the magnet is not at constant velocity but falls from rest through the solenoid? Think about it before watching the video below. Induced emf due to magnet falling through solenoid using Addestation Datalogger

One of my all time favourite TED talks Nikola Tesla was isolated at his death. Would we consider his a success though with all his contributions to mankind?

Jim Al-Khalili does such a great job presenting a chronological flow of events. From electrostatics, to current of electricity, to the link to electromagnetism. Great resource to look at how a CRO was used to record the voltage of the Torpedo Marmorata, as well as Galvani's frog leg experiments. Also there is some discussion about how Faraday discovered the first motor . Despite only receiving formal education till he was 12, Faraday had a great thirst for knowledge and discovery.