D$8\mathrm{.}7.$ A solid conductor of circular cross section is made of a homogeneous nonmagnetic material. If the radius $a=1mm,$ the conductor axis lies on the $z$ axis, and the total current in the $a_z$ direction is $20$ A $,$ find: $($a$)H_{}$ at $=0\mathrm{.}5mm$; $($b$)B_{}$ at $=0\mathrm{.}8mm$;$(c)$ the total magnetic flux per unit length inside the conductor; $(d)$ the total flux for $<mn>0</mn><mn>.</mn><mn>5</mn><mi>m</mi><mi>m</mi>$; $($e$)$ the total magnetic flux outside the conductor.

Ans. $1592\frac{A}{m}$;$3\mathrm{.}2mT$;$2Wb$;$0\mathrm{.}5Wb$;$$