What is the magnetic field around a long, current-carrying 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.

 

[Kruum]

I'm currently using my PDA so no complex equations.But you'll need to use the Gaussian surface for magnetic field.

 

[nlightner]

The magnetic field around a long, current-carrying wire can be determined using the Law of Biot-Savart. This law states that the magnetic field at a point in space is directly proportional to the current flowing through the wire and inversely proportional to the distance from the wire. The direction of the magnetic field can be determined using the right-hand rule, where the thumb points in the direction of the current flow and the curled fingers point in the direction of the magnetic field.

Inside the wire, the magnetic field is circular and its strength is directly proportional to the current and inversely proportional to the distance from the center of the wire. This means that as you move closer to the center of the wire, the magnetic field becomes stronger.

Outside the wire, the magnetic field follows a similar pattern but is weaker compared to inside the wire. The strength of the magnetic field decreases as you move further away from the wire.

At a distance r from the wire, the magnetic field can be calculated using the equation B = μ0I/2πr, where μ0 is the permeability of free space. This equation shows that the magnetic field is inversely proportional to the distance from the wire.

In summary, the magnetic field around a long, current-carrying wire is circular and its strength is directly proportional to the current and inversely proportional to the distance from the wire. It is stronger inside the wire and weaker outside the wire.