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. P

    RC Circuit - Currents at Timed Intervals

    Homework Statement An uncharged 1.15 uF capacitor is in series, through a switch, with a 4.50-M Ohms resistor and a 24.0- V battery (with negligible internal resistance.) The switch is closed at t = 0 and a current of Ii immediately appears. (Which I calculated to be 5.33 uA.) How long will...
  2. P

    Solve RC Circuit Discharge Homework: 6V, 60Ω, 0.02F

    Homework Statement A circuit consists of 3 components connected between 2 terminals: A 6 V source, a 60 ohms resistor and a 0.02 F capacitor. The capacitor is initially uncharged. The voltage source is turned on. What is the current flowing through the above capacitor after a very long time...
  3. O

    Decay in Energy in an RC circuit?

    Homework Statement They want us to find T, time, when the capacitor has lost 50% of its energy. They give us voltage, capacitance, and resistance. Homework Equations I=I_o(e^(-t/RC)) Q=Q_o(e^(-t/RC)) Potential Energy = Q^2/2C The Attempt at a Solution I have no idea how...
  4. E

    RC circuit maximum voltage

    i can't figure this out. In an RC circuit, why is the maximum voltage of a capactior greater then the maximum voltage of a resistor? can anyone guide me in the right direction
  5. E

    Engineering Capacitance for a parallel RC circuit

    Homework Statement A circuit consists of a Zener diode, capacitor and resistor in parallel. Voltage to be maintained across the components is 4.7V, power 5mW. Find the values for resistor and capacitor Homework Equations (Below) The Attempt at a Solution I found the resistance by...
  6. D

    RC Circuit Potential and Current Calculation at Time=0 and Infinity

    Homework Statement Okay, I don't EXACTLY remember the problem statement or the circuit diagram, but I believe I can give enough information to do the problem. On this past quiz, I got 75/100, where there are 4 parts: 2 short answer, 1 part multiple choice, 1 part group test. I got 25 on MC...
  7. C

    Engineering RC Circuit capacitor charge Help

    [SOLVED] RC Circuit Help Homework Statement What is the potential of point a with respect to point b in the circuit shown when switch S is open? Which point, a or b is at a higher potential? b.) What is the potential (after a long time) of point a with respect to ground when switch S is...
  8. T

    Archived RC Circuit: Phase & Magnitude of Current

    Homework Statement Given an RC circuit which has a Capacitor (C=6\times 10^{-6} F) and a resistor (R=5 \Omega) conected in series to an a.c. voltage source of the form v=V_{0} e^{j\omega t} with a V_{0}=1 Volt. Frequency f=10kHz a)What is the phase of the current with respect to the applied...
  9. V

    RC circuit analysis using phasors

    Homework Statement I can't post pictures as I do normally, so you'll have to deal with the cumbersome attachment method! It's just a simple RC circuit. Resistor on top, capacitor on right side with the sinusoidally varying voltage source on the left...
  10. T

    Calculating time constant in RC Circuit

    Homework Statement You see this trace on your oscilloscope for an RC circuit. The vertical scale is 5volt/square and the horizontal scale is 50ms/square. What is the time constant of the RC circuit? Homework Equations Vc(t) = Vo(e^(-t/RC) Vr(t) = -Vo * e^(-t/RC) t halftime = Tln(2) =...
  11. B

    Analyzing an RC Circuit with a Sudden Switch Closure

    Homework Statement In a circuit, the switch S has been open for a long time. It is then suddenly closed. Determine the time constant (a) before the switch is closed (b) after the switch is closed. (c) let the switch be closed at t=0. Determine the current in the switch as a function of...
  12. P

    Engineering Solve RC Circuit Using Laplace Transforms

    Find v(t) at t=800ms for the circuit in Figure 1. Ans: 802mV Writing a single node equation we have \frac{v(t)-2tu(t)}{5}+0.1\frac{dv}{dt}=0. Taking the Laplace transform we have L\left\{ \frac{v(t)-2tu(t)}{5}+0.1\frac{dv}{dt}=0\right\} . tu(t)\Rightarrow\frac{1}{s^{2}}...
  13. D

    Measuring RC Circuit Voltage: Understanding Why CRO is Used

    Why the voltage across the capacitor can be measured by connecting a CRO across both the resistor and capacitor ? actually,i have think of the phase difference and the overall resistance.Still,i can't find the answer.May I get some hints from you?
  14. R

    Calculating Charge on a Capacitor in an RC Circuit

    Homework Statement A capacitor is charged to 1 coulomb; the capacitance is 9.00×10-5 farads. Then a switch is closed which puts the capacitor in a closed circuit with a resistor; the resistance is 9.0x10^1 ohms. Calculate the charge on the capacitor after 4.00 milliseconds. (1 ms = 0.001 s)...
  15. M

    Engineering Natural response of an RC circuit with two capacitators.

    Homework Statement I'm supposed to find the voltage v0(t) for t > 0 for the following circuit: http://img516.imageshack.us/img516/5858/circuitta7.jpg Homework Equations The first part of the excercise was to find the current io(t). I did this by using the node-voltage method to find the...
  16. S

    How Do I Calculate the Charge Over Time in Simple RC Circuits?

    Ok, if I have a Battery B, Resistors R1, R2, and Capacitor C in this circuit: (the ...'s just represent empty space, spaces were getting eaten when I previewed the post) |----------R1--------| |......| B+......| B-......C |......| |---------R2---------| is this...
  17. A

    How Long Does It Take for Charge to Reach 1/e of Maximum in an RC Circuit?

    Homework Statement A 1.47 micro F capacitor is charged through a 123 Ohm resistor and then discharged through the same resistor by short-circuiting the battery. While the capacitor is being charged, find the time for the charge on its plates to reach 1/e of its maximum value. Homework...
  18. N

    Engineering Understanding a RL - RC circuit

    I´m trying to understand a circuit that is build like this: ----###R1###---###C###---- ###---------###----------### -----###L###---###R2###--- How am I supposed to find what frequency (not f=0) the impedance is pure resistive? What I´ve read has it something to do with the resonant...
  19. M

    Solving RC Circuit Problem: A Beginner's Guide - Mankku

    Hi everybody! This is my first post, happy to be a part of this forum! I have a problem that may be pretty easy to solve, and a few years ago I could've myself, but at the moment I'm stuck. I enjoy fiddling with electronics during my free time, and I'd like to study the use of a capacitor to...
  20. C

    Engineering Solve RC Circuit Problem: Initial Conditions & t1 >> 0

    Hello All, I'm having problem to solved the attached RC circuit. The initial conditions are: VC1(0)=V, VC2(0)=0, and the qeustion is what will be the VC2 after t1 (t1>>0)? but i always get VC2(t1)=V which is imposible. I'm solving it by using i=cdv/dt 3. The Attempt at a...
  21. M

    Solve RC Circuit 6V Battery, 1F Capacitor, 3 Resistors

    1. A 6V battery is connected to a 1F capacitor and 3 resistors (R1=1, R2=4, R3=2) R1 is is series with the battery. A junction then appears after R1, which creates 3 different paths, 2 for each remaining resistor, and another for the capacitor. After a long time, what is the magnitude of the...
  22. T

    What is the time constant for an RC circuit discharging?

    Homework Statement http://img515.imageshack.us/img515/7671/untitledtu4.jpg The Attempt at a Solution I really don't know how to tackle this question, but here is my attempt anyhow (wrong I know! :yuck:) RC=5000*2*10^-6 RC=0.01 V=Vo*e^(-t/RC) 0.99=e^(-t/0.01) ln(0.99)=-t/0.01...
  23. O

    A (probably) simple RC circuit question

    Its been 30 years since my last Physics course so while I have the basic concepts I'm uncertain how to solve my current problem: I need to operate a pair of 12V solenoids (.5 seated amps, 4 watts each) with a periodic on/off cycle that gently ramps to full voltage (over about .5 to 1 sec) and...
  24. D

    Engineering RC Circuit + Dependent Voltage Source

    Homework Statement http://img167.imageshack.us/img167/7747/picture2mg7.png Homework Equations iL(t) = current through inductor Using The Step by Step Method: Assume the solution iL(t) = K1 + K2*e^(-t/tau) where K1 = iL(infinity) and K2 = iL(0+) - iL(infinity) so, Assume the...
  25. D

    Engineering Solving RC Circuit Pulse with Step-by-Step Approach

    Hi, I have this problem to do for HW. I did what it asked for, or so I think. I think I may have made a mistake somewhere, it's telling me its not correct. Can you check it out? BTW, I have to use the step by step approach. I'm assuming my solution will be v(t) = K1 + K2 * e^(-t/RC). I then...
  26. D

    Engineering RC Circuit (Quick Glance please, mostly theoretical)

    Hi guys, I have a lab I have to do for an introduction to 1st-order networks. Can you perhaps check my work? I'm pretty sure most of it is correct. I have attached a PDF file, so you can see my lab. Thanks guys. (it's not that long, it'll take at most 1-2min)
  27. B

    Applying a square wave (from 0 to 5V) on a RC circuit

    Hi, I am working with capacitor now and I have this question. I am applying a square wave (from 0 to 5V) on a RC circuit. At the output ( at the resistor) I get a positive and negative values? why is that ? I am suspecting the fact that the capacitor create a phase difference of -90...
  28. J

    Understanding Charge Formulation in Discharging RC Circuits: A Quick Question

    So, I understand the charging of an RC circuit perfectly, but I am a tiny bit bothered by one part of the formulation of charge on a capacitor plate as a function of time for a discharging capacitor in a simple RC circuit (charged with one battery, one resistor and one capacitor all in series...
  29. M

    Calculating Phase Shift for a Series RC Circuit

    Homework Statement A resistor of 362 Ohms is connected in series with a capacitor of 50.0 µF capacitance. A sinusoidal signal of f = 11.7 Hz experiences an impedance of 452.836 Ohms. Find the phase shift between the current and voltage at f = 11.7 Hz. Homework Equations I tried using...
  30. S

    RC Circuit Problem: Find I1, I2, I3 and Q

    Homework Statement In Figure P18.50, suppose that the switch has been closed for a length of time sufficiently long enough for the capacitor to become fully charged. (R = 12.0 k, R2 = 17.0 k, R3 = 1.00 k, V = 9.70 V) The picture is under attachment a) Find the steady-state current in...
  31. A

    Cascading RC circuit w/ DC voltage. How will capacitors charging time vary?

    In the following schematic, will the RC time constant be the same for all capacitors using the equivalent resistance of all the resistors? When I plug it into pspice or electronics work bench, it has that the First capacitors voltage as a function of time will always be twice as much as the...
  32. B

    Energy in a capacitor in an RC circuit.

    The question asks: For a charging circuit, the emf supplied by the battery is 200 V, R = 2*10^5\omega and C = 50 \mu F. Find: a) the time taken for the charge to rise to 90% of the final value b) the energy stored in the capacitor at t=RC c) the power loss in R at t=RC I've worked out...
  33. T

    RC Circuit - Current, Emf, Etc

    Doin a question based around RC circuits and was in a bit of a bind, lookin for some help. The capacitor in the figure below begins to charge after the switch closes at t = 0s. a) what is deltaVc when t >> 0 after switch is closed? b) what is Qmax in terms of emf, R and C? c) in this...
  34. Cyrus

    RC Circuit Voltage: Why So Low?

    I gota quick question for my lab report. We did an RC circuit for my electronics class. The capacitor charged to about 4.51 volts. The source was 5 volts. In theory, it should reach 5 volts as t goes to infinity. What should I write as to why it was under the source voltage by a large amount...
  35. H

    Calculate the time constant (RC circuit)

    Hi. How am I supposed to calculate the time constant for the enclosed circuit diagram. I know time constant t = 1/RC In this case do i take only one resistance or the combined value (series value) Assume any values. I only want to understand how it is to be done. PS: Sorry for the stupid...
  36. C

    Solve Parallel RC Circuit Diff Eq | Current Flow

    I have an RC circuit driven by a voltage source. The resister and capacitor are in parallel. I'm having a problem figuring out the governing differential equation for the current of the circuit. I could figure it out easily if it were a series circuit as the current is the same for each...
  37. D

    Solve RC Circuit: Find Unknown Capacitor Value

    The circuit is (10K ohm resistor in parallel with unknown Capacitor) which are in series with a 4.7k ohm resistor and a 0.1microF capacitor. V_in is applied over the entire circuit and V_out is taken over the 4.7k ohms and 0.1microF. So here is the question. In the circuit...
  38. D

    What is the missing value in this parallel RC circuit problem?

    Parallel RC Circuit Problem! Hey I've been working on this circuit for hours and can't figure out 1 value. This is exactly what was given to me on the page so i have no other information lol. All that was written was: find the values of Zt,It,I1,I2,Vc1 Ive found all the other values...
  39. E

    RC circuit with complex exponential

    I am stuck on this... Given a circuit: current source (Is(t)), R , C - all parallel; Is(t) = e^jt, Vs(t) = 223.6e^j(t - 63.43), Vs(t) is voltage across the current source, which I assume to be the same across R and C since they are ||. Find R and C. (ans: 500 Ohm, 4mF) My attemp was to...
  40. W

    Calculating Work Done with a Series RC Circuit with Variable Plate Spacing

    hey everyone just joined! glad to be here! i just don't get one part of the question and once i get it, i should be able to get the rest. A battery with an emf of 20 volts is connected in series with a resistor of 300,0000 ohms and an air-filled parallel-plate capacitor of capacitance 6...
  41. K

    Solving an RC Circuit with 68.0% Charge in 0.980s

    A capacitor in an RC circuit is charged to 68.0% of its maximum value in 0.980 s. What is the time constant of the circuit? >> I know the time constant is equal to Q/(Q/t) and that t = 0.980 s. I also know that Q = CE and E is a constant. But they don't tell me the capacitance to use... Bah...
  42. J

    RC Circuit and 120 V battery

    A current is released from a 120 V battery. The current passes through a resistor of 1200 ohms and then the current splits into two different capacitors. C1=2.0 uF C2=3.0 uF. If there is no charge on the capacitators before the current is released, determine the charges of Q1 and Q2 on...
  43. G

    Solve RC Circuit: Find Capacitor Value

    Hi, I am stuck on a question to work out the value of a capacitor, The Question is: A capacitor and a 2Kohm resistor pass the same current when each is separately connected across a 100Hz power line. What is the value of the capacitor?
  44. S

    What is the significance of the RC time constant in a simple RC circuit?

    Hello there, I m very new to the forum n doesn't know that much manners of this forum.. I actually want to do a question... we did a practical in our university in which we determined the unknown resistance by using a neon flash bulb... I have to submit a report on that..i have to...
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