State the relationship between the tangential component of the magnetic field B summed around a closed curve C and the current Ic passing through the area enclosed by the curve. A long cylinder conductor of radius R carries a current I along its length. The current is uniformly distributed throughout the crosssection of the conductor. Calculate the magnetic field at a distance r = R/2 from the axis of the conductor. Find the distance r > R from the axis of the conductor where the magnitude of the magnetic field is the same as at r = R/2.
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