The circulation of the induction of a constant magnetic field through a closed circuit in a vacuum is equal to the current through the surface bounded by this circuit, multiplied by µ₀. Please provide examples that support this law.
Use it to solve the following problems:
a. An infinitely long straight wire of radius r flows current I. The current is distributed evenly over the wire cross-section. Find the magnetic field induction inside and outside the wire.
b. A long, wide busbar with a cross dimension of a flows a current evenly distributed over the cross-section of the conductor. Current density j. How does the magnetic field induction depend on the distance x to the median plane of the tire?