Magnetism Definition – Introduction

One of the most important facts in physics is magnetism. We know magnetism’s definition in the basic level that doesn’t make deep sense about how magnetism really works in a relativistic atomic or sub-atomic level. Very few books of electromagnetism can explain about this. And on the contrary, many students remain confused about magnetism to the level of atomic or sub-atomic level. We will learn today in App Atlantis blog about that magnetism definition simply.

Magnetism Definition – Connection With Special Relativity

If you’re not well-familiar with Einstein’s theory of relativity, there’s no way to really explain this theory here. The most effective one could do is provide you with rules steeped in concepts like “electromagnetic field” and “Lorentz invariance”. In fact, this is often not what you are after. For The “Atomic Explanation of Magnetism With Relativity“, Special Relativity is Very Important.

The fact is, magnetism is nothing but electrostatic physics combined with the special theory of relativity. The unfortunate but true fact is, you will not find so many books explaining this – either the authors erroneously believe Mysterious Maxwell’s Equations don’t have any justification and should be accepted without checking, or they’re too involved in their own esoteric notation to pause to contemplate what it is they’re expressing. The sole book I do know of that treats the fact properly is Purcell’s Electricity and Magnetism, which was recently re-released in a very third edition. (The second edition works simply fine if you can find a copy).

Relativistic Atomic Explanation of Magnetism – Some Basic Ideology To Understand

To understand the relativistic atomic explanation of magnetism, a brief, heuristic definition of the idea is as follows.

Suppose, there’s a line of negative charges moving in the z coordinate axis in the positive direction – in a current wire. Think about a positive electric charge q placed at (x,y,z)=(1,0,0), moving in the same z-direction. We will see that there’ll be some electrostatic force on q because of all those charges.

But, to understand Relativistic Atomic “Magnetism Definition” let’s attempt to try one thing crazy – let’s slip into q’s frame of reference. After all, the laws of physics had a higher hold for all points of view. Clearly, the electric charges constituting the current are going to be moving quickly. However, in spite of everything the Coulomb force clearly does not care about the velocity of the electric charges, only on their separation. But the special theory of relativity tells us something else.

It says if we view the scenario from the q’s frame of reference positive charges will seem to appear nearer together. If they were spaced apart by intervals Δz within the original frame, then in this new frame they’ll have a spacing Δz/√(1−v2/c2), where v is q’s speed within the original frame. This is the known length contraction predicted by the special theory of relativity. As q is moving along with the negative charges, at the same speed, from q’s frame of reference negative charges will seem to appear not moving at all. On the other side, the separation of positive charges will seem to appear contracted.

Magnetism Definition – Relativistic Atomic Explanation of Magnetism

If the positive charges appear nearer together, then clearly q can feel a higher static force from the z coordinate axis as a whole. It’ll experience an extra force within the positive x-direction, far from the axis, over and above what we might have predicted from simply sitting within the laboratory frame. This extra force is the magnetic force. Basically, Coulomb’s Law is the only force working on a charge, However, only the charge’s reference frame is valid for using this law to work out what force the charge feels.

Rather than perpetually transforming back and forth between frames, we discover the magnetic field as a mathematical device that accomplishes an equivalent thing. If outlined properly, it’ll entirely account for this abnormal force seemingly experienced by the charge while we are observing it not in its own reference frame. Within the example I simply went through, the right-hand rule tells you we must always ascribe a magnetic field to the current circling around the z-coordinate axis such that it’s pointing to the positive y-direction at the location of charge q. The velocity of the charge is to the negative z-direction, and then qv ×B points to the positive x-direction, just as we learned from dynamic reference frames.

Conclusion – Relativistic Atomic Explanation of Magnetism

This is how in the relativistic atomic/subatomic level magnetism works. Or how magnetism works in the relativistic world. This Atomic explanation of magnetism might help to understand in deep. Highly recommended is reading the book Purcell’s Electricity and Magnetism.

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