Quantitative evaluation of coupling factor and its application

A numerical analysis of the coupling factor k, its applicable examples, and new formulas are described. A formula of ´reflectivity gamma ´ of the magnetic flux, i.e., the ratio of the induced flux to the incident flux in a secondary coil whose winding is closed or in a metal conductor, has been derived in the process of theorizing k. In its straightforward application to nondestructive inspection, the varying component K, behaving like a vector, in impedance of a sensor coil resulting from a metal, is analyzed from a somewhat different point of view, and the locus of K, according to the distance from a specimen with eddy currents, is approximately in a straight line. A gamma -diagram due to a superconductor in the intermediate state is presented as an experimental example of K.