Magnetic field lines and magnetic flux density

[Dale]

My posts here have been made with reference to the opening post and to one concept only, the concept of field lines.

Yes, this is a problem. The standard you apply to the concept of field lines is an impossible standard. If you were to apply that same standard to Newton’s laws you would also conclude that they are “very flawed”. You should apply your same standard to other concepts and see if the standard makes sense. To me, it is clear that the standard you are using to state that the concept of field lines is very flawed is not a valid standard

 

[Herman Trivilino]

That may be true but I don't see the relevance of the comment.

If the one concept you're referring to is flawed for the reason you stated, then every concept in physics is flawed because the same reason applies to every concept. Thus your claim infers that all physics concepts are flawed.

 

[Herman Trivilino]

So use the concept of field lines if it helps. But remember that the concept is very flawed.

The concept is not flawed. It's just that it has to be applied with care, and that it's easy to misunderstand and misapply the concept. This is true of every physics concept.

 

[Dadface]

Yes, this is a problem. The standard you apply to the concept of field lines is an impossible standard. If you were to apply that same standard to Newton’s laws you would also conclude that they are “very flawed”. You should apply your same standard to other concepts and see if the standard makes sense. To me, it is clear that the standard you are using to state that the concept of field lines is very flawed is not a valid standard

It seems to me you are taking things out of context by selecting just certain parts of my posts only. That's very unfair. My criticism of the concept of field lines focuses on one specific area this being where people use the concept to make quantitative predictions. The concept used quantitatively does not work. Am I really setting an impossible standard by pointing that out? Am I wrong in criticising equations of the type:
Flux = number of field lines etc
That equation is wrong in every respect. It doesn't even give a unit for flux.

 

[Dadface]

If the one concept you're referring to is flawed for the reason you stated, then every concept in physics is flawed because the same reason applies to every concept. Thus your claim infers that all physics concepts are flawed.

The concept is not flawed. It's just that it has to be applied with care, and that it's easy to misunderstand and misapply the concept. This is true of every physics concept.

Of course the concept, like every other concept in physics, has to be applied with care.

It seems to me that some people here don't like my use of the word "flawed" so rather than getting involved in semantics I will refer to the word domain as a summary of the concept of domain of applicability.

And its true that different concepts can have different domains. But what strikes me as odd is that there are numerous people who go, or have gone, beyond the domain of the concept of field lines by using the concept to write certain incorrect equations. This thread was started by someone who referred to such an equation.

 

[hutchphd]

Definitions such as the one above don't make sense and that seems to be the reason why the person who wrote the opening post got confused. The concept of field lines, though useful, has shortcomings that don't seem to be realized by the people who write the bad definitions.

I could not agree more.
When one represents the field by drawing "lines" (which I shall continue to call flux lines!), they are always distributed so that their density is proportional to the local field strength. There is nothing within the definition of a"field line" that requires this constraint, and without it they show only the local direction of the field...not nearly so useful.
I truly don't understand the controversy here.