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sophiecentaur

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As you mention a Clamp-on Ammeter, you are clearly considering pretty low frequencies then the practicality of your experiment would mean that the frequency response of your Ammeter would be too soggy to observe the rapid pulse of current at switch on without a significant series L..

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berkeman

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As you mention a Clamp-on Ammeter, you are clearly considering pretty low frequencies

That's true for the transformer-based clamp-on probes for use with AC Mains. But I use a LeCroy Hall effect clamp-on meter in our Lab, and it works from DC-50MHz.

With no inductance in the circuit the magnetic field will collapse.

No, the magnetic field from the current flowing in the wire will be the same, given the same current level. The magnetic field that a clamp-on probe measures comes from the current flowing in the wire it is clamped onto.

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sophiecentaur

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Some AC clamp on ammeters are good enough only up to 400-500 Hz. Readings at 1 kHz can be quite off with them. Do you measure circuit at steady state AC power or want to measure its' transient response? What exactly is your circuit and how do you know resonant freq is below 1 kHz?

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sophiecentaur

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What sort of Capacitance are you using in your calculations? Resonant frequency is 1/(2π√(LC))

C in Farads and L in Henries; you have to include the 'micros' and 'picos' in this.

What Inductance Meter did you use to measure the inductance of a short loop of wire, btw?

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Probably you have situation where adding the cap decreases or increases overall impedance/reactance of the circuit. That depends on paralell or series connection of two reactive components with respect to the source. That's a normal thing, your ammeter is OK.

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Svein

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No, that is not quite true. What happens is that a energy flows from current in the inductance to voltage across the capacitor and back again. Since the voltage and current is 90° out of phase, no power is involved. The amplitudes can be quite high, though.In a series LC resonant circuit the capacitor acts to cancel out the inductance of the the circuit.

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sophiecentaur

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But it's true that the Reactance of one will cancel out the reactance of the other at resonance.No, that is not quite true. What happens is that a energy flows from current in the inductance to voltage across the capacitor and back again. Since the voltage and current is 90° out of phase, no power is involved. The amplitudes can be quite high, though.

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