\mu Consider the cylindrical conductor with a hollow center and copper wals of thickness b-a as shown. The radil of the inner and outer walls are a and b respectively, and the currert I is uniformly spread over the cross section of the copper (shaded region). What is the magnitade of the magnetic field in units of nT at r=23cm.
a=18,1cm,b=30,7cm,I=268mA
\mu _(0)=4\pi \times 10.7T(m)/(A)
Provide your answer with two decimal places:
Yanit: ◻