How Does Current Affect Magnetic Fields in and Around a Wire?

[Master J]

A long, current carrying wire has a radius R and current I.
What is the magnetic field inside, and outside the wire?


Now, if it asked what is the field a distance r from the wire, I could simply use the Law of Biot & Savart (mu.I/2.pi.r). I havn't dome electricity in a while and I am stuck on this one.

I am sure its simple, I just need a nudge.

Thanks guys.

 

[LowlyPion]

Where will the current elements be carried on the wire? And as they are in motion consider the current elements on opposite sides of the wire and what their contribution would be to the field within the wire.

 

[nlightner]

The magnetic field of a long, current-carrying wire can be described by the Biot-Savart law, which states that the magnetic field at a point is proportional to the current, the distance from the wire, and the direction of the current. The formula for the magnetic field inside the wire is given by B = (mu.I/2.pi.r), where mu is the permeability of the medium, I is the current, and r is the distance from the wire.

Inside the wire, the magnetic field will be circular and its strength will decrease as you move further from the center of the wire. Outside the wire, the magnetic field will also be circular, but its strength will decrease much more rapidly. This is because the wire acts as a source of the magnetic field and the strength of the field decreases with distance from the source.

The direction of the magnetic field can be determined using the right-hand rule, where the thumb points in the direction of the current, and the fingers curl in the direction of the magnetic field.

In summary, the magnetic field inside the wire will be circular and will decrease with distance, while outside the wire it will also be circular but will decrease more rapidly. The direction of the magnetic field can be determined using the right-hand rule.