Voltage over a capacitor in a RC-circuit.

In summary, the reason why the voltage over the parallel-connection containing the capacitor is Vc= Q/C is because it is the same as the voltage on the capacitor alone. This is because both components are connected between the same nodes, and the only field present is an electric field set up by the charges on the capacitor plates. Since electric fields are conservative, the work done on a test charge is the same for all routes, resulting in the same potential difference or voltage.
  • #1
Nikitin
735
27
Why is the voltage over the parallel-connection containing the capacitor Vc= Q/C

It makes a little (intuitive) sense to me, but I would like to see the proof if possible. Thanks.
 

Attachments

  • bilde.JPG
    bilde.JPG
    39.8 KB · Views: 398
Last edited:
Physics news on Phys.org
  • #2
Why is the voltage over the parallel-connection containing the capacitor Vc= Q/C

Are you asking...
1) why is the voltage on the capacitor = Q/C?
or
2) why is the voltage on the parallel combination of R and C the same as the voltage on the capacitor alone?
 
  • #3
I'm asking 2.
 
  • #4
The voltage must be the same because both components are connected between the same nodes.
 
  • #5
And if you want to know why the voltage must be the same between the same two nodes, the reason is that the only field we're dealing with here is an electric field set up by the charges on the capacitor plates. But an electric field is a conservative field, meaning that if we take a test charge between two points, A and B, in the field, the work done by the field on the charge is the same for whichever route we go from A to B. So the work done on the test charge per unit charge it carries, i.e. the potential difference or voltage, is the same for all routes. In your case the routes of interest are via the capacitor and via the resistor!
 

What is a RC-circuit?

RC-circuit stands for Resistor-Capacitor circuit. It is an electrical circuit that contains a resistor and a capacitor, and is commonly used in electronic devices such as filters, amplifiers, and oscillators.

What is voltage over a capacitor?

Voltage over a capacitor refers to the potential difference between the two plates of a capacitor. It is measured in volts and is a result of the stored electrical charge on the capacitor.

How is voltage over a capacitor calculated in a RC-circuit?

The voltage over a capacitor in a RC-circuit is calculated using the formula V=Vi(1-e-t/RC), where Vi is the initial voltage, t is time, R is the resistance, and C is the capacitance.

What happens to the voltage over a capacitor in a RC-circuit when the capacitor is fully charged?

When the capacitor is fully charged, the voltage over the capacitor will be equal to the input voltage. This is because no more charge can be stored on the capacitor, and the voltage will remain constant.

How does the resistance in a RC-circuit affect the voltage over a capacitor?

The resistance in a RC-circuit affects the voltage over a capacitor by determining the rate at which the capacitor charges. A higher resistance will result in a slower charging rate and a lower voltage over the capacitor, while a lower resistance will result in a faster charging rate and a higher voltage over the capacitor.

Similar threads

  • Electromagnetism
Replies
7
Views
872
Replies
7
Views
2K
Replies
9
Views
380
Replies
3
Views
937
  • Electromagnetism
Replies
7
Views
1K
Replies
7
Views
1K
Replies
7
Views
1K
Replies
7
Views
1K
Replies
9
Views
3K
  • Introductory Physics Homework Help
Replies
20
Views
256
Back
Top