Thankyou both very much for your help.
Yikes! I'm embarassed about that. It must seem like I didn't spend long thinking about it but really I never think to re-read a question. I'm just surprised I didn't notice when I was typing it out.
For 10mm from centre, I got the answer but not the way...
Homework Statement
A long, straight copper pipe of inner diameter 16mm and outer diameter 24mm carries a current of 100A. Calculate the magnetic flux density at distances i)5mm, ii)10mm and iii)15mm from its axis?
Answer : i)0, ii)9*10^-4T iii) 13.3*10^-4T
Homework Equations
I...