Problem 3.277

An infinitely long wire with a current $I$ flowing in it is located in the boundary plane between two non-conducting media with permeabilities $\mu_{1}$ and $\mu_{2} .$ Find the modulus of the magnetic induction vector throughout the space as a function of the distance $r$ from the wire. It should be borne in mind that the lines of the vector $B$ are circles whose centres lie on the axis of the wire.