# Homework Help: J notation impedance

1. Oct 27, 2011

### lubo

1. The problem statement, all variables and given/known data

We have a capacitor in parallel with an inductor. These are both in series with a resistor and capacitor.

Calculate the J notation Impedance of the network. I only want the initial basic solution.

The problem I have is that sometimes the J notation of C is -ve and sometimes +ve ?

2. Relevant equations

3. The attempt at a solution

Product/sum of the parallel cct:

jwL x 1/jwC/jwL*1/jwC This is the Inductor and capacitor impedance equation.

The above will be added to:

R -j(1/wC)

My question is therefore, why in the above example at product over sum would it be ok to say jwL x 1/jwC/jwL*1/jwC i.e. * a +ve 1/jwC

When below it I can add it to R and -j(1/wC)

I hope this makes sence, thanks for any help in advance.

Last edited: Oct 27, 2011
2. Oct 27, 2011

### tiny-tim

hi lubo!
ah, but the first j is on the bottom, while the second is on the top …

and -j = 1/j