Electromagnetism without any finger

In summary, when it comes to using the right-hand rule with electromagnetism, some visualisation can make it easier to understand, but it is ultimately necessary to remember the directions of fields caused by currents.
  • #1
lalbatros
1,256
2
When I was a student, I remember that I disliked a lot these finger exercises.
I soon realized that these were totally useless, and I solved everything without any finger rule.
But since, I have forgotten how I did ! I only remember that I concentrated on currents, nothing else.

Have some of you also avoided playing with fingers, and how ?

Michel
 
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  • #2
Are you referring to the right-hand rules?

All those tell you is the direction of the cross product of two vectors in the conventional right-handed coordinate system.

You can just understand where the respective vectors are pointing and which direction the appropriate cross product will point.

Of course if you actually take the cross product mathematically, the resulting vector will obviously tell you its direction.
 
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  • #3
lalbatros said:
When I was a student, I remember that I disliked a lot these finger exercises.
I soon realized that these were totally useless, and I solved everything without any finger rule.
But since, I have forgotten how I did ! I only remember that I concentrated on currents, nothing else.

Have some of you also avoided playing with fingers, and how ?

Michel

I usually imagine myself facing the plane of interest, and clockwise rotation in that plane results in going forward through the plane, counterclocwise results in coming out, and vice versa ... sort of like how a clock would turn clockwise if you went forward in time and counterclockwise if you went backwards in time. I know it's sort of vague but its not hard to apply it to anything involving the right hand rule with E&M.
 
  • #4
Hmm...it isn't hard to visualize even without fingers.
 
  • #5
Greg825,

I agree that some visualisation can make finger rules or corkscrew rules easier.
But is that needed after all? Physically, fields are caused by currents. The finger rules are only needed because of conventions taken by physicists to allow them to think about fields and forget (temporarily) about the currents that caused them.

Doesn't that mean that, going "back to the basics", it should be possible to avoid completely these rules? For the benefit of pedagogy, maybe.

Michel
 
  • #6
Yes; the directions of various things in EM (such as propagation, given direction of E-field and B-field) will always be perpendicular. Whether or not we say parallel or anti-parallel to that direction is positive is a convention, which is often easily learned using the "right-hand-rule".

But we will always need some sort of convention, and using cross products/right-handed co-ordinate system is ideal.
 
  • #7
lalbatros said:
Greg825,

I agree that some visualisation can make finger rules or corkscrew rules easier.
But is that needed after all? Physically, fields are caused by currents. The finger rules are only needed because of conventions taken by physicists to allow them to think about fields and forget (temporarily) about the currents that caused them.

Doesn't that mean that, going "back to the basics", it should be possible to avoid completely these rules? For the benefit of pedagogy, maybe.

Michel

I think you're right, they should be avoidable, but are the physical reasons behind why a current creates a magnetic field at all really understood (let alone why it occurs in whichever direction)? I mean similarly to gravity, which is modeled very well, but not really explained.

But maybe you meant avoidable for a reason other than that kind of understanding? I'm not sure of exactly what you mean.
 
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  • #8
Greg825,

My reasons have little to do with ultimate understanding.

It is just that I remember how these conventions were far from real physics. For example, how emf induces a current may need to chain two 'finger' rules, while the end result is well known. I don't think there are examples where their use is really helpful, if one is willing to forget a little about it. In addition, now that differential geometry becomes popular, I have the feeling the 'old stuff' may be reconsidered.

Am I right, and how to write that down?

Michel
 

1. What is electromagnetism without any finger?

Electromagnetism without any finger is a theoretical concept that explores the behavior of electromagnetic fields without the presence of any human or artificial influence.

2. How is electromagnetism without any finger relevant to scientific research?

By studying electromagnetism without any finger, scientists can gain a deeper understanding of the fundamental properties of electromagnetic fields and their interactions with matter.

3. How does electromagnetism without any finger differ from traditional electromagnetism?

In traditional electromagnetism, the presence of a human or artificial finger can affect the behavior of electromagnetic fields. In contrast, electromagnetism without any finger removes this external influence and allows for a more pure study of the phenomenon.

4. What are some potential applications of electromagnetism without any finger?

Applications of electromagnetism without any finger include the development of new technologies and materials that utilize electromagnetic fields, as well as advancements in fields such as astrophysics and quantum mechanics.

5. Are there any current experiments or studies being conducted on electromagnetism without any finger?

Yes, there are ongoing experiments and studies in various fields of science, such as particle physics and material science, that involve studying electromagnetism without any finger to gain new insights and make advancements in our understanding of the universe.

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