Many textbooks derive the dependence of the on-axis field at a point x from the center of
a so-called short solenoid of length 2L and radius R.
HRW chooses neither to derive it nor to provide it as a homework exercise!
So what is it?
"http://www.physics.udel.edu/~watson/phys208/30-spec.html"
Last updated Oct. 29, 1997.
Copyright George Watson, Univ. of Delaware, 1997.