Looking for capacitive reactance but missing "C"

  • Thread starter tessie0407
  • Start date
  • Tags
    Reactance
In summary, the conversation discusses finding the capacitive reactance Xc for a capacitor circuit with a frequency of 1000Hz. The formula Xc = 1/2∏ƒC is mentioned, but the question arises of where to find C when it is not explicitly given. The conversation also briefly mentions the equations for current and voltage, as well as determining peak voltage and peak current. The solution is provided as finding the reactance from the graph and using the formula Xc = ΔVc/I to calculate Xc.
  • #1
tessie0407
7
0
1. Current and voltage graphs are shown for a capacitor circuit with ƒ=1000Hz.
What is the capacitive reactance Xc?




2. I know the equation is Xc= 1/2∏ƒC to solve for capacitive reactance but where do I find C? All of our in class examples had C and ƒ given.



The Attempt at a Solution

 

Attachments

  • 20140722_171959-1[1].jpg
    20140722_171959-1[1].jpg
    18.4 KB · Views: 363
Physics news on Phys.org
  • #2
tessie0407 said:
2. I know the equation is Xc= 1/2∏ƒC to solve for capacitive reactance
That formula is not correct. You need a pair of brackets to set it right or you'll never get the right answer!

What would be the equation for current if you connect that capacitance C to an AC voltage source V volts?
 
  • #3
tessie0407 said:
1. Current and voltage graphs are shown for a capacitor circuit with ƒ=1000Hz.
What is the capacitive reactance Xc?

2. I know the equation is Xc= 1/2∏ƒC to solve for capacitive reactance but where do I find C? All of our in class examples had C and ƒ given.

The Attempt at a Solution


Get the reactance from the graph.


What are peak voltage & peak current?
 
  • #4
The only other thing I can think to do is rearrange ΔVc= I*Xc

Xc= ΔVc/I
Xc= 10V/10x10^-2 A which gives me 100Ω
 
  • #5
tessie0407 said:
The only other thing I can think to do is rearrange ΔVc= I*Xc

Xc= ΔVc/I
Xc= 10V/10x10^-2 A which gives me 100Ω
10V looks right for the voltage. But that's not the right way to write 10mA.
 

1. What is capacitive reactance?

Capacitive reactance is a measure of the opposition to the flow of alternating current (AC) through a capacitor. It is measured in ohms and is directly proportional to the frequency of the AC and the capacitance of the capacitor.

2. How is capacitive reactance calculated?

Capacitive reactance can be calculated using the formula XC = 1/(2πfC), where XC is the capacitive reactance in ohms, f is the frequency in hertz, and C is the capacitance in farads.

3. What factors can affect capacitive reactance?

The two main factors that can affect capacitive reactance are frequency and capacitance. Higher frequencies and larger capacitance values will result in a higher capacitive reactance.

4. Why is "C" missing when looking for capacitive reactance?

The letter "C" is commonly used to represent capacitance in equations and calculations. However, it may be missing if the context or formula only requires the use of capacitive reactance and not the actual capacitance value.

5. How is capacitive reactance used in real-world applications?

Capacitive reactance is used in various electronic circuits and devices, such as filters, oscillators, and power supplies. It is also an important factor in determining the resonance frequency of a circuit.

Similar threads

  • Introductory Physics Homework Help
Replies
2
Views
1K
  • Introductory Physics Homework Help
Replies
9
Views
9K
  • Introductory Physics Homework Help
Replies
16
Views
1K
  • Introductory Physics Homework Help
Replies
9
Views
1K
  • Introductory Physics Homework Help
Replies
2
Views
1K
  • Introductory Physics Homework Help
Replies
6
Views
2K
  • Engineering and Comp Sci Homework Help
Replies
21
Views
2K
  • Introductory Physics Homework Help
Replies
5
Views
1K
  • Introductory Physics Homework Help
Replies
4
Views
1K
  • Engineering and Comp Sci Homework Help
Replies
5
Views
1K
Back
Top