NOTE – The relative permeability is a scalar quantity μr in an isotropic medium and a tensor quantity μ → → r MathType@MTEF@5@5@+=feaagCart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbbjxAHXgaruavP1wzZbItLDhis9wBH5garmWu51MyVXgaruWqVvNCPvMCG4uz3bqee0evGueE0jxyaibaieYdi9WrpeeC0lXdi9qqqj=hEeeu0lXdbba9frFj0xb9Lqpepeea0xd9s8qiYRWxGi6xij=hbba9q8aq0=yq=He9q8qiLsFr0=vr0=vr0db8meaabaGacmGadiWaaiWabiabciaafiaakeaacuaH8oqBgaWcgaWcamaaBaaaleaaieaacaWFYbaabeaaaaa@3C92@ in an anisotropic medium. It equals 1 in vacuum.