Coefficient Of Coupling Relation Between M L L — the NEET Physics formula with its derivation, variables, validity constraints and worked solver.
Coefficient of Coupling (Relation between M, L₁, L₂) Applies to two magnetically coupled coils or circuits. Used to calculate Mutual Inductance when Self Inductances and coupling efficiency are known. Magnetic flux from coil 1 is proportional to current I1: Φ₁ ∝ I₁. Flux linking coil 2 is a fraction of flux from coil 1: Φ₂₁ = kΦ₁. Mutual Inductance is defined via flux linkage: M = (N₂Φ₂₁) / I₁. Self Inductances are defined as L₁ = (N₁Φ₁) / I₁ and L₂ = (N₂Φ₂) / I₂. Combining these expressions yields M = k√(L₁L₂). 0 ≤ k ≤ 1 (k cannot be negative or greater than 1). L₁ and L₂ must be positive real numbers. Assuming k = 1 always (ideal coupling), whereas in practice k < 1 for air-cored coils. Thinking Mutual Inductance is independent of the spatial orientation of the coils (which changes k). Confusing the units of M and L (both are Henry).