Electrical impedance - what is it?

[CaptainPanic]

I'm recently trying to pick up some knowledge about electrical circuits, and one concept that keeps coming up is the "electrical impedance". No matter how much I read about it, it doesn't seem to solidify in my head.

 

Can anyone say in layman's words what it means? I have read the wikipedia, and some other articles, so I was hoping that someone could explain it to me without using mathematical terms.

 

Is there any way I can see impedance with a simple experiment at home (using basic electric components: resistors, capacitors, (AC) power source, etc.)?

[swansont]

Impedance is the AC version of resistance that is seen in resistors in DC circuits. But in AC circuits, capacitors and inductors also impede the current flow, taking/storing some energy, in a way that depends on the frequency.

 

You will get a resonance in a circuit where the impedance is minimized, depending on the L (inductance) and C (capacitance) values. At lower frequencies the capacitor dominates the impedance, and at higher frequencies the inductor dominates.

[CaptainPanic]

Thanks! That's the level of complexity I was looking for... You gave me a simple explanation, and also a few "new" (to me) keywords to continue the google-research

 

Funny that I never knew that a coil is also called an inductor.

[ParanoiA]

Read up on Reactance (X). That's what we call impedance in AC devices. To distinquish between Resistance in DC circuits.

 

Impedance is the sum of Reactance and Resistance.

[ecoli]

Read up on Reactance (X). That's what we call impedance in AC devices. To distinquish between Resistance in DC circuits.

 

Impedance is the sum of Reactance and Resistance.

I think there's something wrong with what you've written here... Perhaps that it's because the magnitude of the impedance it's a vector sum of the impedance of the various components of an RLC circuit that the last sentence doesn't look right to me.

[swansont]

It's the sum in quadrature.

[ecoli]

It's the sum in quadrature.

potato potato.

[ParanoiA]

Well, reactance is the "resistance" of the RLC circuit, so while we have juicy equations to figure that, reactance is that final result.

 

It's been a decade since I've accessed this information in my noggin, so maybe I'm wrong. I seem to remember determining total impedance by figuring the resistance of the DC components and adding that to the reactance of the AC circuit with a given frequency and so forth.

 

I probably shouldn't have replied. It's bad to lead someone in the wrong direction.

[thedarkshade]

The general resistance of the circuit of the alternative current represents impedance. It is marked with Z and it is:

[math]Z=\sqrt{R^2 + (R_L - R_C)^2}[/math]. You can derive this equation from the graph which contains all the three thermogenic, inductive and capacitive resistances, and by applying Pythagoras theorem in that.

 

If you want to calculate the intensity now it goes like:

 

[math]I_0 = \frac{U_0}{Z}[/math] and now it looks like:

 

[math]I_0=\frac{U_0}{\sqrt{R^2 + (\omega L - \frac{1}{\omega C})^2}}[/math]

[Tahmid]

Hi, captain panic.

what i know is that we say resistance in DC. this resistance is called impedance when the power supply is AC. But in DC, inductors and capacitors do not let current flow through them. But in AC, current can flow through inductors and capacitors. Capacitors filter the incoming signals as well. The inductor makes the current rise slowly(but the current does flow)!