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Negative pole of magnet deflects electrons?

  1. Sep 28, 2010 #1
    I watched a video there about cathode ray tubes and the guy in the video demonstrated the negative pole of a magnet deflecting the beam and the positive pole attracting the beam. I know that moving electrical charges create magnetic fields but I didn't know their magnetic fields always deflect negative magnetic poles. I'm having trouble visualizing this. Doesn't a moving electron have a positive and negative magnetic pole just like any other particle?
     
  2. jcsd
  3. Sep 28, 2010 #2
    Poles of magnets neither attract nor repel beams of moving electric charges. Magnets do deflect beams, but in a direction perpendicular to the magnetic field. The force on the beam is always perpendicular to the direction of motion, so the beam is bent into a circle.

    So the force on the beam is perpendicular to both the magnetic field and the direction of motion.

    I attach a thumbnail photo of an electron beam in a vacuum tube being bent into a circle by a pair of Helmholtz (magnetic solenoid) coils.

    Bob S
     

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