Magnetic field around wire

Discussion in 'Supporting Physics' started by hadley, Feb 12, 2020.

  1. What do you set up to demo this?
     
  2. For demo, I have an acrylic base with a vertical wire, 4V DC. it sits on an OHP (Yes. I still have some) or under the bench camera.
    I set half a dozen plotting compasses around. I have similar bases with coils and a solenoid.
    For practical. I have some 6" x 4" pieces of hardboard with a central hole,that can be supported by a stand and clamp.
     
    Mark and Nick Mitchener like this.
  3. Nick Mitchener

    Nick Mitchener COMMITTEE

    we only do it as a demo with plotting compasses.
     
  4. STEM1

    STEM1 Dave

    You can use mini plotting compasses placed in a small circle around a vertical wire. Takes a fair bit of current though. Iron filings works but gets messy!
     
  5. karen b

    karen b COMMITTEE

    I have a single wire and a coil mounted in Perspex that goes on an overhead projector with either a plotting compass or iron filings
     
  6. Again here's one I made a lot earlier lol
    IMG_0907.JPG
     
  7. Thanks! Each of our teachers seem to want something different so hoping to standardise it
     
  8. In a similar vein to Dr J's marvelous contraption, this was made by my predecessor. It also has a slide in frame with magnadur magnets on to show the catapult field with iron filings. It's still in regular use. We also use the vertical wire mounted on perspex with plotting compasses, viewed on OHP or visualiser.

    012.JPG
     
    KeithD likes this.
  9. Nick Mitchener

    Nick Mitchener COMMITTEE

    That's only the second application I have ever seen for that power supply. I used it to make a shaded pole motor from a beer can after I saw it on twitter. I have no idea what it was originally bought for.(I have a suspicion that nor did the purchaser, we bought all sorts of stuff in one year in the 90s when we had a load of dosh)
     
  10. We have a number of these supplies and I tend to use them where I want a bomb proof, high current, continuously variable low voltage PS. Generally things involving electromagnetism. It's part of my setup for remagnetising magnets in conjunction with a large capacitor and a coil. Also for showing drift velocity of coloured ions on filter paper where the higher voltage is useful. They're chuffing heavy though!
     
  11. Nick Mitchener

    Nick Mitchener COMMITTEE

    I only have one, hadn't thought about drift velocity. I have used a lantern battery top cockroft walton multiplier for that though so I can stick a few thousand volts across a damp filter paper.
     
  12. Nice to see that you do the drift velocity demo. It's always a huge surprise to the pupils how slowly the ions move.
     
  13. Nick Mitchener

    Nick Mitchener COMMITTEE

    It used to be in the old OCR A level, but the practical isn't in the new one, depends which teacher does it but I should point out we can do it and encourage it more.
     
  14. Love the "old" unilab 0-25 V PSUs we have a few kicking about and tend to be my go to power supply , only thing I ever found they don't do well apart from electronics ( in a classroom situation too easy to turn up the voltage and fry stuff ) and the blue unilab microwave horns the 0-25V units are too smooth!!! the unilab ranger units give a much better "buzz" from the output amp