Do magnetic lines of force accurately represent magnetic fields?

  • Context: Undergrad 
  • Thread starter Thread starter nottheone
  • Start date Start date
  • Tags Tags
    Force Lines Magnetic
Click For Summary

Discussion Overview

The discussion centers on the existence and representation of magnetic lines of force in relation to magnetic fields. Participants explore whether these lines are a physical reality or merely a conceptual tool used to illustrate magnetic behavior, drawing parallels with topographical maps and their contour lines.

Discussion Character

  • Exploratory
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions the existence of magnetic lines of force beyond the classic demonstration with iron filings, seeking additional proof.
  • Another participant compares magnetic lines to contour lines on a topographical map, suggesting that while they are not visible, they represent a real quantity in the magnetic field.
  • A different viewpoint suggests that the alignment of iron filings does not prove the existence of actual field lines, proposing instead that field lines are a conceptual construction meant to represent magnetic behavior.
  • One participant emphasizes that fields are continuous and that contour lines and field lines are discrete representations, arguing that a magnetic field exists even between the drawn lines.
  • Another participant speculates that reducing the size of iron filings would make the magnetic field lines less apparent, indicating a potential variability in how field lines are perceived.

Areas of Agreement / Disagreement

Participants express differing views on the existence and nature of magnetic lines of force, with no consensus reached regarding their physical reality versus their conceptual utility.

Contextual Notes

Participants rely on analogies and conceptual frameworks, which may depend on specific interpretations of magnetic fields and representations. The discussion does not resolve the underlying assumptions about the nature of magnetic fields and their representations.

nottheone
Messages
81
Reaction score
0
Do magnetic lines of force actually exist and if so is there any proof of distinctive lines other than the classic magnet and iron filings on paper?
 
Physics news on Phys.org
Have you ever seen or heard of a topography map? This is a map that shows the contours of the land, a contour line follows along a constant level of elevation. If you walk along a hill side there are no contour lines drawn on the ground. BUT the path of constant elevation is there.

The same with magnetic lines, we cannot see them but the quantity they represent is there. Now what do you think? Do magnetic field lines exist?
 
This is a good question because Iron filings around a magnet are often used in schools and textbooks to introduce the notion of field lines. I have though about this too and come to the following conclusion (I stand to be corrected on this): The allignment of Iron filings is due to the magnetisiation of the individual filings; I don't think this proves that actual field lines exist. Field lines are a conceptual construction (like the example of contours on a map) intended to represent (rather than explain) the behaviour of a magnet.
 
Fields are continuous; contour lines and field lines are merely discrete, representations of them.

Take for instance a hill and its representation on a map. The map shows discrete lines showing regions of the same elevation, and are (depending on the scale of the map) usually spaced at a certain interval of maybe 10m, 50m or 100m of elevation. But if you were to try and visualise the hill from those contour lines, you know that it's not just a series of steps; the surface of the land varies between those lines with a slope.

It's much the same with field lines and magnets. There is still a magnetic field between your 'field lines', it's just that the magnetic filings disperse in this pattern (probably as the previous poster suggest due the attraction of individual filings to its nearest filing). I'm willing to bet that as you reduce the filing size the less obvious those 'field lines' become.
 

Similar threads

High School How is a magnetic field formed in a space surrounded by one pole?
  • · Replies 3 ·
Replies
3
Views
2K
High School A Magnetic Misconception on Divergence 0/Closed Field Lines?
  • · Replies 3 ·
Replies
3
Views
1K
Undergrad Is this analogy between Magnetic Force and Gravitational Force accurate in helping to understand what contributes more to a stronger magnetic force?
  • · Replies 11 ·
Replies
11
Views
2K
Undergrad How Do Magnetic Forces Differ Between Magnets and Wires?
  • · Replies 1 ·
Replies
1
Views
2K
High School Seeing both B field lines and E field lines at the same time
  • · Replies 22 ·
Replies
22
Views
3K
Undergrad Geometry of Magnetic field lines as they approach a magnet pole?
  • · Replies 28 ·
Replies
28
Views
3K
Undergrad Directional magnetic field
  • · Replies 9 ·
Replies
9
Views
2K
High School Basic Straight Line Permanent Magnet Accelerator
  • · Replies 3 ·
Replies
3
Views
3K
Undergrad Biot Savart law gives us magnetic field strength or magnetic flux density?
  • · Replies 1 ·
Replies
1
Views
2K
Undergrad Force between opposing magnets
  • · Replies 7 ·
Replies
7
Views
2K