# Homework Help: Calulating voltage across a resistor

1. Jan 12, 2009

### wormvortex

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

what is the total impedance and voltage across the resistor at this frequency?

The type of circuit is a simple circuit with a high pass filter connected. The filter is rated at 10nF, the resistor is 1Kohm and the power source is 10v AC

2. Relevant equations

the frequency for the circuit I've worked out previously to be 16Khz.

3. The attempt at a solution

for working out the impedance I've been using the formula:

which gave me 1/(2piX16khzX10nF) which I worked out to be 994.7ohms. Think I've got that bit right but not entirely sure. As for the voltage I'm not sure at all as to what formula I should be using in order to calculate it? If any one does anwser please don't give the answer using my figures as I'd like to work it out for myself. Though an example would be appreciated :)
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Jan 12, 2009

### Delphi51

The circuit isn't clear to me. Is the capacitor in parallel or in series with the resistor?
The impedance of the resistor is given - 1 k ohm.
Perhaps you want to find the impedance of the resistor and capacitor in parallel/series - if so you must consider the reactance you have for the capacitor AND the resistance. How do you combine resistance and reactance to get impedance?

The second part depends very much on what the circuit is. I expect you will have to use V = IZ to find the current for starters.

Last edited: Jan 12, 2009
3. Jan 12, 2009

### wormvortex

Probably easier to explain if I just show you the circuit :)

http://img231.imageshack.us/img231/3558/p1201092133st6.jpg [Broken]
http://g.imageshack.us/img231/p1201092133st6.jpg/1/ [Broken]

Only want to find the impedance of the resistor(which is what I've had a go at) and the voltage across the resistor.

Last edited by a moderator: May 3, 2017
4. Jan 13, 2009

### Redbelly98

Staff Emeritus
Welcome to PF wormvortex

I think they want the impedance of the total circuit (capacitor & resistor together), and the voltage across the resistor.

Asking for the impedance of a 1 kΩ resistor would be too easy.

5. Jan 13, 2009

### wormvortex

doesn't mention the capacitor at all in the question so don't think it's asking me to find it.

6. Jan 13, 2009

### Redbelly98

Staff Emeritus
It asks for "total impedance". As I interpret the question, "total" would include the capacitor.

But if you think otherwise, I won't argue the point any further.

7. Jan 14, 2009

### Redbelly98

Staff Emeritus
Just out of curiousity, were you able to get the voltage across the resistor?