What is Rc circuit: Definition and 394 Discussions

A resistor–capacitor circuit (RC circuit), or RC filter or RC network, is an electric circuit composed of resistors and capacitors. It may be driven by a voltage or current source and these will produce different responses. A first order RC circuit is composed of one resistor and one capacitor and is the simplest type of RC circuit.
RC circuits can be used to filter a signal by blocking certain frequencies and passing others. The two most common RC filters are the high-pass filters and low-pass filters; band-pass filters and band-stop filters usually require RLC filters, though crude ones can be made with RC filters.

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  1. M

    Engineering Analyzing an RC Circuit: Solving for Time Constants and Resistance

    Homework Statement Ok guys, so this is a slightly long question, but bear with me because I think I figured out most of it. I just need help towards the end. So I have a circuit with a current source in parallel with a capacitor and also in parallel with a resistor (see attached image). This...
  2. O

    Electronics: Plot Vout of RC circuit

    Homework Statement http://imgur.com/OowiMCR As noted in the image: In the circuit below, R1=R2=10kΩ, and C=0.1μF. Plot Vout(t) if the input, Vin, is a step function of height V0 at t=0 Homework Equations Vcap=V0-Ce-t/RC The Attempt at a Solution I was hoping someone could...
  3. B

    RC circuit with Schmitt trigger - Derivation

    In lectures I covered how a Schmitt trigger can be used in an RC circuit to determine the capacitance of the capacitor (Where the Schmitt trigger switches at 0.3V+ and 0.6V+). The equation given was that C = 1.2 R \ T (time period) Does anyone know how to derive this or where it comes from...
  4. J

    Engineering RC Circuit Analysis: Find di/dt & Show Current=0 After 1 Time Constant

    Homework Statement Use current equation and find di/dt expression, hence show if initial gradient were maintained the current would be 0 after 1 time constant. Homework Equations I calculated RC to be 0.5s i=0.02e^-t/0.5 The Attempt at a Solution I solved di/dt to be...
  5. F

    Building a RC circuit to pick up radio waves

    Homework Statement Homework Equations w = 1 / sqrt(LC) The Attempt at a Solution hi there, I 1. I decided to choose, 93.3 MHz so 93.3 x 10^6 Hz is my freq. 2. I googled how a band pass filter diagram should look like and I found this, is the only way to create a low...
  6. T

    RC Circuit defibrillator Question

    Homework Statement A 140μF defibrillator capacitor is charged to 1500 V. When fired through a patient's chest, it loses 95% of its charge in 40 ms. What is the resistance of the patient's chest? Homework Equations The Attempt at a Solution According to "Mastering Physics," the solution that...
  7. N

    RC Circuit Filtering Halp?

    I bought a biophysics book the other day, and immediately began reading it. Sadly, I'm only 12 pages in now, because I seem to have run up against a wall in my understanding. You see, I don't understand a step being taken in the math, and am not sure what I should learn to understand it better...
  8. L

    RC circuit question(Charging A Capacitor)

    Homework Statement C1= 2.0 μF C2= 5.0 μF the resistor has a resistance of 0.10 MΩ The circuit shows the charging of a capacitor a) At t=0 the switch is closed. What is the initial measuring on the ammeter? b) After the current has decayed to zero what are the voltages at points A,B and C...
  9. O

    Understanding RC Circuits and Voltage Distribution

    Homework Statement Given V R C for the figure, determine a. The voltage of a with respect to b when the switch is open? b. Which point a or b is at a the higher voltage? c. What is the final voltage of point b with respect to ground when the switch is closed? d. Wow much...
  10. E

    Engineering RC circuit differential equations

    Homework Statement Task is to write differential equation for this circuit. Homework Equations The Attempt at a Solution I'll try to solve the task, but now I want to know, is it possible to use voltage source instead of current source. For example, I can calculate ekvivalent...
  11. U

    Maximum Length for Coaxial Cable in a 100 ns Noise Transfer Scenario

    Homework Statement Signals from sources of different kinds are often very weak and very quick. To minimize the noise risk they're often led through coaxial cables. How long can one [coaxial cable] be if it has the capacitance 80pF / m and resistance 0.04 Ohm/m and you want to transfer noise...
  12. Z

    Engineering Finding the Transfer Function of an RC Circuit in the Laplace domain

    Hi, Basically I have circuit with an input Vi (s) across a capacitor C which is in parallel with a resistor R1. And these 2 components are in series with another resistor R2 (please see attached drawing). The question states: Show that the transfer function of the circuit is: Vo/Vi...
  13. E

    Energy Dissipation in an RC Circuit: Finding the Total Thermal Energy

    Homework Statement A capacitor C=8.00*10^-8F which has an initial charge q=1.4*10^-6C starts to discharge through a resistor R=3.00*10^6Ω at time t=0. Determine the total energy W dissipated as thermal energy in the resistor. Hint: use energy conservation. The Attempt at a Solution I...
  14. F

    Series-Parallel RC Circuit Analysis

    I'm having a hard time understanding and solving problems in moderately complex RC circuits... Please Help. You don't have to solve right up to the numerical value, that is not my priority, Rather If you could just explain how to begin and process through the question, It would be best...
  15. F

    Series-Parallel RC Circuit Analysis

    I'm having a hard time understanding and solving problems in moderately complex RC circuits... Please Help. You don't have to solve right up to the numerical value, that is not my priority, Rather If you could just explain how to begin and process through the question, It would be best...
  16. I

    Using Kirchhoff's rule in RC circuit while charging

    Hello I have a conceptual question about using Kirchhoff's voltage rule to derive expression of the charge in the RC series circuit when it is being charged by certain EMF. Usually most books start by writing the equation \mathscr{E}-iR-\frac{q}{C}=0 But when the charging is going on...
  17. P

    Can the Impedance of Series RC and Parallel RL Circuits be Equal with Same R?

    Homework Statement Can a series RC circuit and a parallel RL circuit have the same impedance if the R is the same in both? What would the values of R, L and C have to be if they can? Why/why not, physically speaking? Homework Equations Zr=R Zc=1/iwC ZL=iwLThe Attempt at a Solution I know in...
  18. P

    Power in the components of an RC circuit as a Function of time

    Homework Statement A simple RC circuit with an EMF source ε, Resistor R and capacitor C are in series. When the switch is closed find the rate of energy stored in the capacitor, the power dissipated in the resistor, and the power supplied by the emf as functions of time. Homework Equations...
  19. P

    Multi-loop RC circuit, 2 batteries, 7 resistors, 1 capacitor

    Homework Statement For the multi-loop circuit as shown, assuming the capacitor is initially uncharged, find the currents in each of the resistors at t=0 after the switches are closed. So I believe there are 8 unknowns really because of the 8th branch with the capacitor. If you look at the...
  20. M

    Solve Charging RC Circuit: Find Capacitor Charge at t1

    Homework Statement Switch is initially opened with the capacitor uncharged. At t=0 the switch is clsoed. At time=t1 later, the potential difference between A and B is 2.00volts Find the charge on the capacitor at time t1. R=10,000ohms C=2.4nF Vb=12volts VA->B-=2.00volts Homework...
  21. M

    Time it takes for a RC circuit to fully charge

    Homework Statement How much time does an RC circuit require to become fully charged assuming that the capacitor was initially uncharged. resistance = R capacitance = C Voltage = V Homework Equations Q=CV(1-e^(-t/RC)The Attempt at a Solution so T = -ln(Q/(CV) - 1)RC but Q = 0 since it's...
  22. H

    Finding the Resistance in an RC Circuit

    Homework Statement A 10-µF capacitor is charged by a 10-V battery through a resistance R. The capacitor reaches a potential difference of 4 V in a period of 3 s after the charging began. Find the value of R.Homework Equations c=q/v q=CE(1-e^-t/RC) i=(E/R)e^(-t/RC)The Attempt at a Solution I...
  23. D

    Engineering Solving for voltage and current on an RC circuit

    Homework Statement Uploaded problem 5 Homework Equations i1=(R2/(R1+R2)) i2=(R1/(R1+R2)) The Attempt at a Solution Are my answers for problem 5 ok?
  24. M

    Understanding Voltage in Parallel RC Circuits

    Hello, I know that if two resistors are in parallel or two capacitors, they have the same voltage. However, is it the case that a resistor and capacitor in parallel also have equal voltage?
  25. G

    Electric Circuit Question - RC Circuit

    Homework Statement http://img163.imageshack.us/img163/6339/rccircuit.png Homework Equations The Attempt at a Solution I'm trying to find the node voltage. I was going to try and solve the problem knowing that the net charge is zero. Q = CV I'm having problems the voltage...
  26. P

    Why Does the Exponential Calculation in My RC Circuit Equation Return 1?

    Homework Statement I'm trying to use the equation for charging capacitor that's discharging, and I can't get the answer right. On the calculator it keeps showing as 1.Homework Equations I(t) = -(1.96) [e^((-9.0*10^(-6)) / (1300)(2.0*10^(-9)))]The Attempt at a Solution My problem is that the...
  27. A

    Engineering Response of RC circuit i/v of capacitor help

    Homework Statement after having been in position 1 for a long time, the switch was moved to position 2 at t=0. determine: a) i-c(0-) and vc(0-) b) i-c(0) and v-c(0) c) i-c(infinity) and v-c(infinity) d) v-c(t) for t>=0 e) i-c(t) for t >=0Homework Equations The Attempt at a Solution not sure...
  28. A

    Voltage drop across capacitor in RC circuit

    Homework Statement Please look at the attachment for the circuit. The question is this: The switch has been closed for a long time. It is then opened. How long does it take for the potential across the 4μF capacitor to fall to half of its initial value? Homework Equations V =...
  29. F

    Solving Two Loop RC Circuit Homework

    Homework Statement A circuit is constructed with four resistors, one capacitor, one battery and a switch as shown. The values for the resistors are: R1 = R2 = 52 Ω, R3 = 41 Ω and R4 = 129 Ω. The capacitance is C = 62 μF and the battery voltage is V = 24 V. 1) The switch has been open for a...
  30. V

    A question about basic parallel RC circuit

    In a series RC circuit, the current flows until the voltage of the capacitor equals that of the source so that the two voltages oppose each other and there's no net flow. In a parallel circuit, the current indeed does stop flowing through the branch the capacitor is attached to (after the...
  31. D

    Engineering RC Circuit Discharge Conceptual Question

    http://i.imgur.com/ZCcaZpq.png I have the solution manual, so this is more just a question of why, rather than what. I understand that with the switch open: vA = 3v vB = vC = 0v i0 = 0.25 mA When the switch closes it creates a short that makes the two 6kΩ resistors irrelevant...
  32. C

    How Do RC Circuits Function with Zero Potential Energy Post-Resistor?

    So we're covering RC circuits in my physics class and I'm having some trouble with the concepts. When you have a circuit with a resistor and a battery, current passing through the resistor produces a voltage drop. If the battery is zero for our potential, the battery imbues the circuit with...
  33. C

    Engineering RC Circuit with switch. Find (discharging?) current

    Homework Statement http://imageshack.us/a/img831/8798/homeworkprobsg31.jpg Assuming that the switch has been in position #1 for a long time; at t = 0 the switch is moved to position #2. Calculate the current i(t) for t>0.Homework Equations Q = CV V = IR V(t) = -V0*e-t/RC (V0 is the...
  34. W

    Capacitor charge in parallel RC circuit

    Homework Statement What is Q(∞), the charge on the capacitor after the switch has been closed for a very long time? a circuit, whose image is attached, has known values for the resistors : R1 = R2 = 72 Ω, R3 = 101 Ω and R4 = 79 Ω, is C = 56 μF, V = 24 V. Homework Equations kirchoff's laws...
  35. W

    How to find Qmax of a capacitor in parallel RC circuit?

    Homework Statement i tried using the usual Q=VC to answer this question for a multiloop RC circuit, "What is Q(∞), the charge on the capacitor after the switch has been closed for a very long time?" and my answer was wrong. clearly, i can't find Qmax because the resistors contribute to the...
  36. G

    How Is Charge Calculated in a Two Loop RC Circuit After the Switch Opens?

    Homework Statement A circuit is constructed with four resistors, one capacitor, one battery and a switch as shown. The values for the resistors are: R1 = R2 = 22 Ω, R3 = 91 Ω and R4 = 129 Ω. The capacitance is C = 40 μF and the battery voltage is V = 12 V. The positive terminal of the battery...
  37. S

    How Do You Calculate Capacitance in a Series RC Circuit?

    Homework Statement Consider a series RC circuit with R = 151 Ω and an unknown capacitor C as shown below. http://www.flickr.com/photos/67342906@N0… The circuit is driven by an alternating electromotive force with εRMS = 174 V at a frequency of f = 7.70 Hz. The current in the...
  38. S

    Why am I having trouble with the RC circuit analysis?

    Hello, I'm trying to analyze the RC circuit... specifically a low-pass filter, so the set up is voltage source to resistor to capacitor, and the voltage source provides an oscillating voltage Vin, whereas I measure Vout across the capacitor. I think I'm getting confused between two different...
  39. F

    RC Circuit: Charges faster than discharges?

    Homework Statement This isn't a problem from a textbook, but it is homework. For a lab in class, we worked with simple RC circuits on breadboards. The strange thing I noticed is that the capacitor always charges faster than it discharges. I know that the Time constant should be T=RC, so I...
  40. N

    Phase Angle Analysis of RC Circuits

    Homework Statement Find the phase angle between the input and output voltages in the following two circuits - in each case state whether the output leads or lags the input voltage. The second circuit is the same but the capacitor and the resistor are switched around. Homework Equations...
  41. 5

    Solving RC Circuit Problem: Find Capacitance from 40V Voltage

    I have a series rc circuit. 80 v battery, capacitor1, resistor1: 10M ohm, capacitor 2, then back to the negative end of the battery. Capacitor 1 and 2 are equal, after a certain time, the voltage on each capacitor is 40.0v. What is the capacitance of each capacitor? Thanks!
  42. Q

    Engineering Transient RC Circuit: Finding i0(t) for t>0 | Basic Problem Solution

    Homework Statement In the following transient circuit, assume at t<0, the circuit is at steady state. Find i0(t) for t>0 http://sphotos-b.xx.fbcdn.net/hphotos-ash3/c0.0.241.241/p403x403/521743_510378412315012_79982992_n.jpg Homework Equations The Attempt at a Solution First...
  43. T

    Solving an RC Circuit Using Differential Equations

    Homework Statement The Attempt at a Solution I tried two different methods and came to an odd conclusion:
  44. L

    RC Circuit, Charging, Question

    Homework Statement Consider the circuit below, where C1=80mF, C2=30mF, R=50ohms and E=5V. At t=0, both capacitors are uncharged - so it's charging. The circuit is in series, with E ---> C1 ---> C2 ---> R ---> (back to) E a) Find the time constant. b) The initial potential...
  45. I

    Engineering Circuit Analysis of driven RC Circuit with short circuits

    Homework Statement Determine the value of the current labeled i and the voltage labeled v at t=0+, t= 1.5 ms, and t = 3.0 ms. Homework Equations Ohm's law: v = i *r Decay in source free RC Circuit v(t) = v@0 * e^(-t/RC) The Attempt at a Solution i(0-) = 0.1 A. Therefore, v across 200 ohm =...
  46. P

    Solving an RC Circuit: Find Time to Reach 65% of Max Value

    Homework Statement An RC circuit has EMF=12.0V, R=15 kΩ and C=3.8 μF. How long does it take for energy stored in the capacitor to reach 65% of its maximal value? Homework Equations 1) Q = Cε 2) Q X .65 = desired charge 3) q(t) = Q(1 - e-t/RC) The Attempt at a Solution This is...
  47. M

    How long does it take for a car to discharge through its tires in a pit stop?

    Homework Statement When the cehicl stop's in the team's pit stop, consider the time as being t=0. If the potential difference between the car and ground is 30kV, the car-ground capacitance is 500pF and the resistance of each tyre is 100Gohm, determine the time it takes for the car to discharge...
  48. T

    RC Circuit ; why RC=(VT/2 delta V)

    Homework Statement I need to prove that RC=(VT/2 delta V) Select the circle components of Charging and discharging of a capacitor Measure the resistance of resistor with a multimeter When you run a different frequency the cycle time change run different frequency that T<<tao, T=tao...
  49. T

    RC Circuit vs Op amp integrator

    I'm still learning about this, but it seems that an RC circuit performs the same function as an op amp integrator (http://www.electronics-tutorials.ws/opamp/opamp_6.html). In other words, they both can be used as integrators/low pass filters. If this is true, why would anyone bother with an...
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