Equivalent electrical circuit considers an empty coil of inductance L₀ in a series with a resistance R₀; show if the coil is completely filled with a spin system characterized by the susceptibility components X (w) and X"(w) that the inductance at frequency w becomes L = [1 + 4πX'(w)]L₀, in series with an effective resistance R = 4πwX" (w) + L₀ + R₀. In this problem X = X' + iX" is defined for a linearly polarized rf field.