Which Magnetic Pole Exerts More Force on Electrons?

  • Context: Undergrad 
  • Thread starter Thread starter vasko
  • Start date Start date
  • Tags Tags
    Electrons
Click For Summary

Discussion Overview

The discussion revolves around the behavior of electrons in a magnetic field, specifically addressing the question of which magnetic pole exerts more force on electrons and the nature of the forces involved. Participants explore concepts related to magnetic and electric fields, as well as the bending of electron beams.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions whether electrons bend towards the positive magnetic pole due to attraction or away from the negative pole due to repulsion.
  • Another participant asserts that the question is flawed, emphasizing that physics focuses on "how" electrons behave rather than "why," and notes that both poles contribute to the magnetic field.
  • A different participant clarifies that electrons are bent by electric fields when near charged objects, not magnetic fields, and explains the perpendicular relationship between the motion of electrons and magnetic fields.
  • It is mentioned that the force on an electron between charged plates depends on its proximity to the plates, with the positive plate exerting increasing attraction as the electron gets closer.

Areas of Agreement / Disagreement

Participants express differing views on the nature of the forces acting on electrons, with some emphasizing magnetic fields and others focusing on electric fields. There is no consensus on the original question regarding which magnetic pole exerts more force.

Contextual Notes

Participants highlight misunderstandings regarding the roles of magnetic and electric fields in influencing electron behavior, indicating a need for clarity on these concepts.

vasko
Messages
2
Reaction score
0
Hi ! First - my apologies, I'm a physics "newbie" and my question may sound quite "stupid" to most of the people here but I'm just wandering about something and hope you can help me - to understand why/if this is true or false.


Say we have a beam of electrons pointed right into the middle of a source of magnetic field.
One of the magnetic poles is "+" and the other is "-". The electrons from the beam should "bend" towards the positive pole since they have negative charge. I believe this was how they were discovered but may be mistaken.

So my question is - how you can 'know' which magnetic pole 'exerted' more force - the positive one - due the attraction with the negative charge of the electrons or the negative one - due the repelling force because of the same charges ?

Does the beam bends because of the "+" magnetic pole attraction or due the "-" magnetic pole repulsion ?

I know that this sounds kind of philosophical and may not matter in the "real world" - say it does :) how you can know which pole is the 'reason' for the bending ? And can you know this at all ?

Of course I assume "perfection conditions" which imply that you are actually able to point the electron beam right into the "middle" of the source of magnetic field.

Thanks in advance !
 
Physics news on Phys.org
Firstly, your question doesn't completely make sense; physics investigates "how" electrons behave rather that "why" they do so. Except for philosophy, I guess the only thing to say is that both poles contribute (since mathematically, the fields of magnetic monopoles would add).

Secondly, you've got the direction of bending wrong.

Welcome to PF! :wink:
 
Last edited:
There's a fundamental misunderstanding here. The electrons will be bent towards a positively charged object and away from a negatively charged object (like the plates of a capacitor). In other words, they are being bent by an electric field (not a magnetic field).

When you shoot an electron into a magnetic field (made by a horseshoe magnet, say), the electrons are bent in a direction that is perpendicular to the magnetic field (and to the path of the electron). In other words, they are not bent towards the north or south poles of the magnet.

If you consider an electron moving between the charged plates of a capacitor, then the force felt by the electron is due to both plates. The positive plate pulls it closer and the negative plates puches it away. Initially, the force will be greater from the plate that the electron is closer to. Eventually, if the plates are large enough, or the electron is moving slowly, the attraction from the positive plate will get bigger and bigger as the electron gets closer and closer to it.

Ref: http://images.google.com/imgres?img...netic+field&svnum=10&um=1&hl=en&safe=off&sa=G
http://spiff.rit.edu/classes/phys213/lectures/inkjet/capacitor.gif
 
Last edited:
Inadequate question :) My apologies. Thanks again !
 
Last edited:

Similar threads

Undergrad Magnetism: Same Pole Repulsion & Heteropolar Attraction
  • · Replies 32 ·
2
Replies
32
Views
3K
Undergrad Geometry of Magnetic field lines as they approach a magnet pole?
  • · Replies 28 ·
Replies
28
Views
3K
Undergrad How induction works within a coil (nuances of it)
  • · Replies 6 ·
Replies
6
Views
2K
Undergrad Charge movement relative to magnetic field frame dependence/invariance
  • · Replies 5 ·
Replies
5
Views
2K
Undergrad Question on Hall Effect and magnetic force
  • · Replies 2 ·
Replies
2
Views
2K
Undergrad Defining the Forces from Magnetic Fields and Electric Fields
  • · Replies 4 ·
Replies
4
Views
2K
Undergrad Explaining the magnetic (cable) paradox
  • · Replies 5 ·
Replies
5
Views
1K
High School Why does a magnet attract metal objects?
  • · Replies 2 ·
Replies
2
Views
2K
High School Which direction does a charged particle move in a magnetic field?
  • · Replies 1 ·
Replies
1
Views
1K
High School Magnetism: Properties, Effects & Uses - 65 Chars
  • · Replies 5 ·
Replies
5
Views
1K