Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Repulsion by an electromagnet

  1. Sep 23, 2014 #1
    Can it be possible that an electromagnet would repel a iron block?? if yes then please explain.
  2. jcsd
  3. Sep 23, 2014 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Only if the iron block is magnetized.
  4. Sep 24, 2014 #3
    according to me the iron block will be magnetized by the field of electromagnet in such a way that it will attract it and if there is no external field then how will it be possible that an electromagnet repels an iron block??
    I saw a video on youtube where electromagnet repels an iron block without any external field.
  5. Sep 24, 2014 #4


    User Avatar
    Gold Member

    If you notice, the electromagnet attracted the iron hammer.
    The silver cylinder and slab are aluminum, as stated in the comments section by the author.

    The author's explanation:

    21 hours ago
    Why can it also push of metal things? And on what does it depend if it pull in or push of?

    mopatin[the author]
    20 hours ago

    With ferromagnetic metals, always attractive (pull).

    With other conductive metals (copper, aluminum) push, because of eddy currents.

    The electromagnet generates a magnetic field. That magnetic field induces a current on the metals that are near. If the metal is open that currents only will flow in small local circles, but if you close the ring the current will flow around the hole ring. That current will generate a magnetic field, because moving charges generate magnetic fields (Oersted, Ampere) and that magnetic field opposes to the former one, the one from the electromagnet (Lenz's Law). This is why the ring is repelled. ​

    Other facts from the comments section:
    This is a transformer from a microwave oven.
    The author powered the coil with 240 vac.​

    Interesting demonstration. I've only ever seen static magnets used to demonstrate this effect.

    The author, according to their twitter account, is from Zaragoza, Spain.
    "DIY, science, technology, experiments, physics, chemistry, ETC"​

    I like that guy. Someone should invite him to PF. :)
  6. Sep 25, 2014 #5
    Got the point.. thank you man and this setup is one of the tremendous setup i have ever watched.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook