How do I calculate the voltage across each capacitor after the switch is closed?

  • Thread starter displayname
  • Start date
In summary, the question is asking for the voltage across each capacitor after the switch is closed, with a previously calculated current of 0.5 A. The relevant equations are Q=CV, Q=Qo*e^(-t/RC), and V=IR. The voltage for the 5 uF capacitor is 20 V, but it is unclear why it is the same as the voltage across the 40 ohm resistor. To calculate the voltage for the 10 uF capacitor, we need to consider the circuit in steady state and identify a resistive voltage divider that is setting the final voltages.
  • #1
displayname
6
0

Homework Statement



Personal question: What is the voltage across each capacitor after the switch is closed?
(It was previously calculated that the current after the switch is closed is .5 A)

naBWs.png


Homework Equations



Q = CV
Q = Qo*e^(-t/RC)
V = IR

The Attempt at a Solution



The answer is 20 V for the 5uF capacitor, but I do not understand why the voltage for the 5 uF capacitor is the same as the voltage across the 40 ohm resistor.

I have no idea how to calculate the voltage for the 10 uF capacitor.
 
Physics news on Phys.org
  • #2
Presumably you're looking for the voltage across the capacitors a "long time" after the switch is closed, after the transients have died away and everything is static?

Consider that at that time the currents through the capacitors will all be zero (we've reached steady state for a DC circuit) , so as far as the resistance network around the capacitors is concerned, the capacitors no longer exist. See if you can identify a resistive voltage divider that's setting the final voltages at key points in the circuit.
 

What is a capacitor?

A capacitor is an electronic component that stores electric charge. It is made up of two conductive plates separated by an insulating material, known as a dielectric. When a voltage is applied to a capacitor, it stores energy in the form of an electric field between the plates.

How does a capacitor work?

A capacitor works by storing electrical energy in an electric field. When a voltage is applied to a capacitor, one plate becomes positively charged and the other plate becomes negatively charged. This creates an electric field between the plates, which can store energy. The amount of charge that a capacitor can hold is determined by its capacitance, which is measured in Farads (F).

What is the relationship between capacitors and voltage?

The relationship between capacitors and voltage is that the amount of voltage that a capacitor can hold is directly proportional to its capacitance. In other words, the larger the capacitance of a capacitor, the more voltage it can hold. This means that capacitors with higher capacitance values can store more energy than ones with lower capacitance values.

Why are capacitors used in electronic circuits?

Capacitors are used in electronic circuits for a variety of reasons. They can be used to filter out unwanted frequencies, store energy, and regulate voltage levels. Capacitors are also commonly used to smooth out the output of power supplies and stabilize the voltage in electronic circuits.

What is the difference between AC and DC voltage when it comes to capacitors?

The main difference between AC and DC voltage when it comes to capacitors is that AC voltage alternates between positive and negative, while DC voltage remains constant. This means that capacitors used in AC circuits have to be able to handle a higher voltage than those used in DC circuits. Additionally, AC capacitors are designed to allow current to flow in both directions, while DC capacitors only allow current to flow in one direction.

Similar threads

Capacitor Questions Charging and Discharging
    • Introductory Physics Homework Help
Replies
4
Views
2K
Electronic Circuits: Capacitors and switches
    • Introductory Physics Homework Help
Replies
11
Views
2K
Capacitor in series voltage problem
    • Introductory Physics Homework Help
Replies
19
Views
2K
Solve RC Circuit Problem 1: V=IR, Q=CV
    • Introductory Physics Homework Help
Replies
11
Views
1K
How long after the switch is closed does the voltage across
    • Introductory Physics Homework Help
Replies
4
Views
2K
Energy dissipated in the resistors in a 2 mesh RC circuit
    • Introductory Physics Homework Help
Replies
1
Views
2K
Capacitors in a circuit with switches
    • Introductory Physics Homework Help
Replies
5
Views
4K
RC Circuit with parallel resistor
    • Introductory Physics Homework Help
Replies
6
Views
1K
What will be the final voltage across the 2 micro-farad capacitor?
    • Introductory Physics Homework Help
Replies
26
Views
2K
Two battery circuit charging one capacitor
    • Introductory Physics Homework Help
Replies
1
Views
3K

Hot Threads

Recent Insights

Back
Top