dl vector is the way we are going
but we can go clock wise and counter clock wise
and in each case i will have a different result
here is a question:
there is endless cylinder i which we only see its crossection in the photo.
its radius is [tex]R_1 a distance d from the center a cylinder with radius [tex]R_2
along the cylinder flows current I in a uniform way inside the page(X).
1.what is the magnetic field in x>0 region?
2.what is the magnetic field in (0, )?
i tried to solve it by amperes law
have i done the first region correctly