Mutual inductance between two coupled coils is given by the relation M = K√L1L2 Where L1L2 = Inductance of the coil K = Coefficient of coupling When K = 1 coils are said to be tightly coupled and if K is a fraction the coils are said to be loosely coupled. Here Kmax =1 Kmin =0 ∴ m ≤ (L1 L2 )0.5
Constantin‘, also known as ‘Eureka wire‘, is the trade-name for a copper-nickel alloy (approx. 60:40 ratio) formulated in the late 1800s by Edward Weston.