Calulating voltage across a resistor

In summary, the question is asking for the total impedance and voltage across a resistor in a simple circuit with a high pass filter. The frequency for the circuit is 16kHz and the power source is 10v AC. The impedance of the resistor is given as 1 kΩ and the circuit includes a capacitor with a rating of 10nF. The attempt at a solution includes using the formula 1/(2piX16khzX10nF) to calculate the impedance, which is determined to be 994.7Ω. The question also asks for the voltage across the resistor, but it is not clear what formula should be used to calculate it. The circuit is shown in an image provided and the question
  • #1
wormvortex
3
0

Homework Statement



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


Homework Equations



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

The Attempt at a Solution



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

0203.GIF


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 anyone 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 :)
 
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  • #2
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.
 
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  • #3
Delphi51 said:
The circuit isn't clear to me. Is the capacitor in parallel 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 - 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?

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:
  • #4
Welcome to PF wormvortex :smile:

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. :wink:
 
  • #5
doesn't mention the capacitor at all in the question so don't think it's asking me to find it.
 
  • #6
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
Just out of curiousity, were you able to get the voltage across the resistor?
 

1. How do you calculate the voltage across a resistor?

To calculate the voltage across a resistor, you can use Ohm's Law: V = IR, where V is voltage, I is current, and R is resistance. Alternatively, you can use Kirchhoff's Voltage Law, which states that the sum of all voltages in a closed loop circuit is equal to zero.

2. What is the unit of measurement for voltage?

The unit of measurement for voltage is volts (V). This represents the amount of electrical potential energy per unit charge.

3. How does the voltage across a resistor affect the current flowing through it?

According to Ohm's Law, the current is directly proportional to the voltage and inversely proportional to the resistance. This means that as the voltage across a resistor increases, the current flowing through it will also increase, and vice versa.

4. Can the voltage across a resistor be negative?

Yes, the voltage across a resistor can be negative. This can occur when the direction of the current flow is opposite to the direction indicated by the voltage source. In this case, the voltage drop across the resistor will be negative, indicating a decrease in potential energy.

5. How can you measure the voltage across a resistor?

You can measure the voltage across a resistor using a voltmeter, which is a type of electrical measuring instrument. A voltmeter is connected in parallel to the resistor and will display the voltage reading in volts.

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