The self-capacitance of a coil is measured by the resonating capacitor. The measurement gives the value of tuning capacitor as C₁ = 460 pF at a frequency.
f₁ = 2 MHz. The second measurement at
f₂ = 4 MHz yields a new value of tuning capacitor, C₂ = 100 pf. The distributed capacitance C_d will be