Electric & Magnetic Field Lines: Why Do They Bow Out?

[zoobyshoe]

This site has a typical representation of the electric field lines between a negative and positive charge:

Electric Field Lines
Address:http://physics.bgsu.edu/~stoner/P202/efield/sld006.htm

Although the lines emerge from one particle and converge on the other, they bow out in between. They don't take the straightest path right from one particle to the other.

This is a drawing, but of course this very same thing can be seen in the electrfied grass seeds floating on oil demonstration some may have seen.

Not particularly surprisingly, magnetic field lines behave the same way. The sprinkled iron powder "fingerprint" of the magetic field reveals that the lines bow out on their way from a North to a South magnetic pole. They don't take the straightest route.

I once had a stack of soft iron rectangles taken from the core of an automobile spark coil. They were all the same size and shape and thickness. they were about a half inch wide by 4 inches long. When I put one end of this stack up against a magnet the end that was in contact with the magnet stuck tight. The other end of the stack spread open. The permanent magnet had induced the same magnetic pole in the other end of all the pieces of metal such that they all repelled each other.

It seems safe to say that the reason that electric and magnetic lines of force bow out in between opposite poles is that, at any given point they all have the same charge (in the electric field) or polarity (in the magnetic field) and therefore repell each other laterally. They will only come back together when the opposite pole or charge overwhelms the lateral repulsion and pulls them together.

So, for the people who know Maxwell's equations, is my assessment correct, or is this bowing of the electric and magnetic fields between charges and poles caused by something else?

 

[eljose79]

I can confirm that your assessment is correct. The bowing out of electric and magnetic field lines between opposite charges or poles is indeed due to the lateral repulsion between them. This is a result of the fundamental forces of electromagnetism, described by Maxwell's equations, which govern the behavior of electric and magnetic fields.

In the case of electric fields, the electric force between two charges is inversely proportional to the square of the distance between them. As the field lines spread out, the distance between them increases, causing the electric force to decrease and resulting in the bowing out of the field lines.

Similarly, in the case of magnetic fields, the magnetic force between two poles is also inversely proportional to the square of the distance between them. This leads to the bowing out of the field lines as they spread out.

It is important to note that this phenomenon is not limited to just two charges or poles, but applies to any system of charges or poles. This is why we see the same behavior in the iron powder "fingerprint" of a magnetic field and in your demonstration with the stack of soft iron rectangles.

In conclusion, the bowing out of electric and magnetic field lines between opposite charges and poles is a result of the fundamental forces of electromagnetism and is accurately described by Maxwell's equations.

 

[Graeme Robinson]

Your assessment is largely correct. The bowing out of electric and magnetic field lines is due to the force of repulsion between like charges or poles. This can be seen in the example of the iron powder "fingerprint" of a magnetic field as well as in your demonstration with the soft iron rectangles.

Maxwell's equations do indeed provide a mathematical explanation for this phenomenon. In particular, the Gauss's law for electricity and the Ampere's law for magnetism show how the electric and magnetic fields are related to the charges and currents that create them. These laws demonstrate that the strength of the electric and magnetic fields decreases with distance, leading to the bowing out of the field lines between opposite charges or poles.

In addition, the Lorentz force law also plays a role in explaining the bowing of field lines. This law states that a charged particle will experience a force in the direction of the electric field and perpendicular to the magnetic field. This means that as the field lines bow out, they are exerting a force on charged particles in the direction of the field lines, causing them to move away from each other.

Overall, the bowing of electric and magnetic field lines is a result of the fundamental principles of electromagnetism and can be explained by Maxwell's equations and the Lorentz force law.