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## Main Question or Discussion Point

Hi everyone,

I seem to be having a little trouble with parallel impedance. I have the equations, but I dont understand why, im not asking for a super proof, just an explanation.

So basically we have a circuit of:

ac source, then a capacitor and resistor in parallel.

the formula that we use is

z = R*(Xc) / sqrt((R^2)+(Xc^2))

my questions is, why cant you just use

1/Z = 1/R + 1/Xc

...Now the research ive done doesnt seems to take me to any clear explanation, one site I saw was talking about how you CAN use that formula, but its actually 1/jXc, and as you cant divide by a complex number you need to get it to a real number, multiple by its conjugate and then you end up with the formula that is correct. I understand...the maths part. But in electronics class we havnt been taught how or why Xc is imaginary.

So im I guess the answer to my question is because you cant divide by a complex number,....but now it seems like a whole chunk of knowledge is missing, as to WHY its a complex number?

...My electronics class is just "fundamentals of electronics" but the lecturer does not go into any detail at all, just gives you the equation and thats it, so there isnt much understanding happening. All the understanding I have is on my own research, while everone else is quite stumped if a slightly different question comes up as they dont understand / cant apply things to different situations...

Anyway, I dont know if im asking for to much? Should I just accept it and thats that?

The way I see it aswell, if you understand whats happening, even if you forgot the actual formulas you can always derive it from the knowledge of whats happening. and then you can use it in different situations.

Thanks for your time.

I seem to be having a little trouble with parallel impedance. I have the equations, but I dont understand why, im not asking for a super proof, just an explanation.

So basically we have a circuit of:

ac source, then a capacitor and resistor in parallel.

the formula that we use is

z = R*(Xc) / sqrt((R^2)+(Xc^2))

my questions is, why cant you just use

1/Z = 1/R + 1/Xc

...Now the research ive done doesnt seems to take me to any clear explanation, one site I saw was talking about how you CAN use that formula, but its actually 1/jXc, and as you cant divide by a complex number you need to get it to a real number, multiple by its conjugate and then you end up with the formula that is correct. I understand...the maths part. But in electronics class we havnt been taught how or why Xc is imaginary.

So im I guess the answer to my question is because you cant divide by a complex number,....but now it seems like a whole chunk of knowledge is missing, as to WHY its a complex number?

...My electronics class is just "fundamentals of electronics" but the lecturer does not go into any detail at all, just gives you the equation and thats it, so there isnt much understanding happening. All the understanding I have is on my own research, while everone else is quite stumped if a slightly different question comes up as they dont understand / cant apply things to different situations...

Anyway, I dont know if im asking for to much? Should I just accept it and thats that?

The way I see it aswell, if you understand whats happening, even if you forgot the actual formulas you can always derive it from the knowledge of whats happening. and then you can use it in different situations.

Thanks for your time.