WEBVTT

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LC circuit, inductor coiled in parallel with a capacitor

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The sinusoidal BF generator supplies the LC resonant circuit

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The LC circuit is in series with a resistor at a point connected to the ground of the oscilloscope

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Red signal, red wire: parallel resonant LC circuit

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Blue signal, blue wire: in parallel on the resistor: image of the intensity

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at 500 Hz the red signal LC is lower and in advance

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The red signal is ahead, so the coil, normal at low frequency, dominates

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When the frequency increases, the red signal increases, Z #X = L * 2 * pi * f

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Until now the inductance is preponderant: the red signal increases, the blue decreases

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Note! The signals are now in phase!

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I decrease f: red returns to front

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And now we are in phase! The blue signal is almost zero! Resonance!

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In zoom just before the beginning ...

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The parallel LC circuit is close to 8000 Ohm!

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A perfect coil in a perfect fit would offer infinity in impedance, 0 in intensity

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Resonac at 3.6 kHz and passage on the other side: capacitive! ZC becomes lower than ZL!

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Resonant circuit or parallel plug: infinite impedance at its resonant frequency

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Impedance increases at resonance: coil and capacitor feed each other

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inductance and capacitor provide the reagent: they have opposed by almost 180 °

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A kernel (screwdriver) changes the resonance frequency because L!