# Magnetic Field generated by a wire

• Ravui
In summary: However, in quantum electrodynamics, the existence of fields is explained by the exchange of virtual particles known as photons. These virtual particles carry the electromagnetic force between charged particles, giving rise to the concept of the magnetic moment and intrinsic magnetism. The motion of electric charges, such as electric currents, and the intrinsic magnetism of elementary particles, such as the electron, are responsible for the creation of magnetic fields. The concept of magnetic fields and their production can be further understood through the principles of relativity and quantum mechanics.
Ravui
So my notes detail how to find the direction of the magnetic field (right-hand grip rule), but how exactly are these magnetic fields produced? They can't just spontaneously come into existence just because there is a current through a wire, right? What properties allow them to come into being?

I checked up wiki already and came across this :

The magnetic moment is due to

(1) motion of electric charges, such as electric currents, and (2) the intrinsic magnetism of elementary particles, such as the electron.

I don't exactly understand what is i)the magnetic moment and ii)the intrinsic magnetism.

Oh and one more thing, is the 'motion of electric charges' referring to the electron spin?

I'm grade 12 so I'd appreciate it if someone would explain it in terms I'd understand.

Thanks :)

Well you kind of already nailed it. Current densities are responsible for the magnetic field. Both $$J$$ and $$\dot{J}$$. The motion of charges, linear motion, spinning ( quantum and angular), and periodic all produce magnetc fields.

As we know from relativity, If a electron is in your rest frame, and I am moving towards that electron, then you will NOT fell the magnetic field, and I WILL. Strange? then you may start to understand what is magnetic field..

Ravui said:
how exactly are these magnetic fields produced? They can't just spontaneously come into existence just because there is a current through a wire, right?

For that matter, how exactly are electric fields produced? They can't just spontaneously come into existence just because there is a charge located somewhere, right?

In both cases, the existence of the field is a postulate of classical electrodynamics. Maxwell's equations tell us the relationships between fields, charges and currents, but do not include an underlying mechanism.

## 1. What is a magnetic field generated by a wire?

A magnetic field generated by a wire is a region of space around a wire where a magnetic force can be detected. It is created by the flow of electric current through the wire.

## 2. How is a magnetic field created by a wire?

A magnetic field is created by the movement of electric charges, such as electrons, in a wire. As the charges move, they create a circular magnetic field around the wire.

## 3. What direction does the magnetic field generated by a wire point?

The direction of the magnetic field generated by a wire follows the right-hand rule. If you point your right thumb in the direction of the electric current, your fingers will curl in the direction of the magnetic field.

## 4. How does the strength of a wire's magnetic field change with distance?

The strength of a wire's magnetic field decreases as the distance from the wire increases. This is described by the inverse square law, which states that the strength of a magnetic field is inversely proportional to the square of the distance from the source.

## 5. Can the magnetic field generated by a wire be controlled?

Yes, the magnetic field generated by a wire can be controlled by changing the amount of electric current flowing through the wire. The strength of the magnetic field is directly proportional to the amount of current in the wire.

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