How to distinguish circuit resonance by experiment

How to distinguish circuit resonance by experiment

When parallel resonance occurs, the input current is the minimum, but the current in the resonance circuit is the maximum. When series resonance occurs, the voltage is the maximum

Which experimental methods can be used to judge whether the circuit is in resonance state

In the experiment, we can judge whether the waveforms of the circuit current and voltage are synchronous (in phase)

On the resonance experiment of AC circuit
In the experiment, in the process of finding f (0), if u (R ') decreases with the decrease of F, then f (0) is larger or smaller than the current frequency. Why?

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Because the value of U (R) is the voltage at both ends of R in the series circuit. The voltage divided by the resistance is equal to the current in the circuit. When the voltage becomes smaller, the current becomes smaller, and the current becomes smaller, it is farther away from the resonance point F (o). If f decreases, it can be seen that the smaller the decrease, the farther away it is from fo. Of course, fo is larger than the current value