Showing magnetic field induced in a wire

Discussion in 'Supporting Physics' started by platypus, Jan 16, 2020.

  1. Does anyone have any top tips for making this demo work (The one with a straight wire and iron filings)? I've been using quite a thick wire but I wasn't sure if thinner wire would be better maybe? Thanks
  2. Need a powerful power pack (at least 3A and 12v) and gently tap the card to shake up the filings so they move into line. You'll need to make sure the wire is long and/or you put a bulb/ammeter in to stop the wire melting/overheating.
  3. We use a short length of 1mm sq wire. Connecting to a power supply with our standard 4mm plug wires.
    Setting the PSU to about 4 Volts.
    You want a current of a couple of Amps, but not high enough to smoke the wires.
    To be honest we only do this with plotting compasses now.
  4. Nick Mitchener

    Nick Mitchener COMMITTEE

    we only do it with plotting compasses too. Filings with a coil sometimes.
  5. use plotting compasses
    20-22 SWG copper wire
    the save saver 2V 8.5A electromagnetic power supply works well for this
  6. Plotting compasses as well here, iron filings should not be allowed anywhere near children, teachers or magnets imho.
    Nick Mitchener likes this.
  7. Thanks for the tips, I'll have a go with these ideas this morning and hopefully I'll get it to work!
    Thanks again :)
  8. You can get sealed, flat packs of filings in something like glycerine. They work quite well at lower currents.
  9. We have a wire that passes through a petri dish held in place with blue-tac to make a platform for plotting compasses to sit on. It's just the standard stuff that 4mm leads are made from but quite long (clamped in a tall clamp stand and with long "tails").
  10. karen b

    karen b COMMITTEE

    We have the Philip Harris demo kits