Confused about a charge going into a magnetic field?

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Discussion Overview

The discussion revolves around the behavior of charged particles in a magnetic field, specifically addressing the application of the right-hand rule and left-hand rule in determining the direction of force on charged particles, such as electrons and positively charged particles. The scope includes conceptual clarification and technical explanation related to electromagnetic theory.

Discussion Character

  • Conceptual clarification
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant describes a scenario where a positively charged particle moves in a magnetic field and applies the right-hand rule to determine the direction of the force acting on it.
  • Another participant questions how the right-hand rule applies to negatively charged particles, specifically electrons, and whether the force direction would be the same or opposite.
  • A participant asks about the relevance of the Lorentz force law in this context.
  • There is a discussion about the relationship between the right-hand rule, left-hand rule, and the concept of the cross product, with one participant explaining that the right-hand rule is used in the context of cross products.
  • One participant expresses skepticism about the need for both left-hand and right-hand rules, suggesting that the left-hand rule should apply to electron beams if used correctly.

Areas of Agreement / Disagreement

Participants express differing views on the application of the right-hand and left-hand rules, particularly regarding their relevance to negatively charged particles. There is no consensus on whether the left-hand rule is appropriate for electrons, and the discussion remains unresolved.

Contextual Notes

Participants reference the Lorentz force law and the mathematical concept of the cross product, but there are no explicit definitions or derivations provided. The discussion includes assumptions about the applicability of the rules to different types of charged particles.

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Say for instance a + charged particle is moving right along the x-axis. Then it will encounter a magnetic field with the direction pointing up. Using the Right hand rule, the force acting on that particle will be going out of the page to me so to speak.

But what if it was an electron with a negative charge? Will it still follow that right hand rule? or will it do the opposite and go into the page? I think it would still be out of the page, but is that right logic?
 
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What does the Lorentz force law say?
 
I have always been wondering why they invent some thing called left hand rule and right hand rule for this and that. Isn't there something called cross product?
 
Yes, the right hand rule is part of the cross product. A cross product takes two vectors and returns a 3rd vector which is perpendicular to the previous two. But there are two such vectors, one determined by the left hand rule and one determined by the right hand rule. The cross product takes the one determined by the right hand rule. So the cross product implies the right hand rule.
 
netheril96 said:
I have always been wondering why they invent some thing called left hand rule and right hand rule for this and that. Isn't there something called cross product?

The Left and Right hand rules are for people who would run a mile at the mention of Vector Products. i.e School Pupils and the like.

The Left Hand rule just HAS to work for electron beams. Why should it not (if you are applying it correctly)?
 

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