{"id":55619,"date":"2025-11-09T06:14:50","date_gmt":"2025-11-08T21:14:50","guid":{"rendered":"https:\/\/phys-edu.net\/wp\/?p=55619"},"modified":"2025-11-09T06:14:50","modified_gmt":"2025-11-08T21:14:50","slug":"why-does-the-magnet-stop-it-unveiling-the-secret-of-change-hating-electricity-with-a-coil-swing-experiment","status":"publish","type":"post","link":"https:\/\/phys-edu.net\/wp\/?p=55619&lang=en","title":{"rendered":"Why Does the Magnet Stop It? Unveiling the Secret of \u201cChange-Hating Electricity\u201d with a Coil Swing Experiment!"},"content":{"rendered":"

I’m Ken Kuwako, Science Trainer. Every day is an experiment.<\/strong><\/span><\/p>\n

Imagine a piece of metal stopping dead in its tracks without anything touching it. Doesn’t that sound like science fiction or magic? What if I told you you could easily experience this phenomenon using just items you already have at home? Today, I\u2019m sharing an experiment recipe that you can do right away at home and is guaranteed to amaze you!<\/p>\n

The key to this phenomenon is the “eddy current.” While the term might sound unfamiliar, eddy currents are actually very close to us and support our daily lives. A great example is the “eddy current brake” used in Shinkansen (bullet trains), some regular trains, and roller coasters at amusement parks. The incredible thing about this brake is that it can stop wheels without any physical contact between parts\u2014it’s like magic! Since it involves no friction, it offers major advantages such as stable braking even on rainy days and minimal wear and tear on parts.<\/p>\n

Today, I’ll introduce an experiment that unravels the true nature of these magical eddy currents!<\/p>\n

The Science Recipe<\/h3>\n

\u25cf What You Need<\/h4>\n
    \n
  • Copper wire (insulated wire like magnet wire is easier to handle)<\/li>\n
  • A core to wrap around (such as an empty can or a cardboard tube from plastic wrap)<\/li>\n
  • A magnet<\/li>\n
  • Alligator clips (or cellophane tape), if available<\/li>\n<\/ul>\n

    Regarding the magnet, a strong one like a neodymium magnet is ideal, but several stacked round ferrite magnets sold at 100-yen shops will also work. The more conductive the copper wire is, the more pronounced the following phenomenon will be.<\/p>\n

    \u25cf Procedure<\/h4>\n

    \u2460 First, create a coil. Use a cylinder, like an empty can, to wrap the copper wire around. A thin can, such as one for soda, is recommended. Wrap it about 20 times. (Note: If using magnet wire, scrape off the insulation at both ends with sandpaper or a utility knife.)<\/p>\n

    \"\u30b9\u30af\u30ea\u30fc\u30f3\u30b7\u30e7\u30c3\u30c8<\/p>\n

    \u2461 Hang the coil to create a pendulum (swing). Secure it to something so the coil can swing like a pendulum.<\/p>\n

    \"\u30b9\u30af\u30ea\u30fc\u30f3\u30b7\u30e7\u30c3\u30c8<\/p>\n

    \u2462 Let the pendulum swing naturally. First, let it swing normally. Naturally, it will continue swinging for a while. Next, connect the two ends of the copper wire using alligator clips or tape (closing the circuit) and observe. Since there is no magnet yet, you should see no change.<\/p>\n

    \u2463 Now, place the magnet near the coil and repeat step \u2462. Position the magnet so that when the coil pendulum swings, the magnet approaches and moves away from the “side” of the coil, rather than passing through the coil’s loop. Then, repeat the observation from step \u2462.<\/p>\n

    \"\u30b9\u30af\u30ea\u30fc\u30f3\u30b7\u30e7\u30c3\u30c8<\/p>\n

    \u25cf The Result<\/h4>\n

    Please check out this video<\/a>.<\/p>\n