any electrical/mechatronic engineering/phys student that can help me with this?

[BigAl]

Hello. I've been typing my report up, which is about resonance in LCR circuit. I find it hard to grasp the fact why the circuit behaves like a inductor at high frequencies and like a capacitor at low frequencies. I mean the potential difference across the inductor is very high compared to that of capacitor at high frequencies and vice versa. Can someone explain the logic behind this? 

[BigAl]

I think I got the answer

[Hancock]

Well this is kind of awkward, because I don't know whether or not this is a pure series RLC circuit, or a 1/2 parallel-half series, or a full parallel RLC circuit.

Regardless, we had to look at complex impedance for this question. Impedence is really an extension from conventional resistance, but it shows the resistance of a device when it is placed under AC conditions. Note that DC voltage is just AC voltage with a frequency of 0.

So,
Z(inductor) = jwL
Z(capacitor) = 1/(jwC)

So, at low frequencies, and therefore low angular frequencies, we will have the inductor having a low impedance, and the capacitor having a very large impedance. This means that the voltage drop across the capacitor becomes very large via ohm's law, V = ZI (where V and I are complex phasors), and the voltage drop across the inductor is very low.

So, if the frequency gets lower and lower, the capacitor's impedance will get larger and larger until it acts as a short circuit. A similar argument can be applied for the inductor with high frequencies.

[BigAl]

Thank you very much. It makes sense with these mathematical expressions.