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.