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. B

    Question on capacitors in an RC circuit

    Homework Statement All information is given in the picture posted Homework Equations V=IR , Q=CV The Attempt at a Solution What I don't understand is , when the capacitors are initially uncharged , they should just be treated as wires , if this is the case , then the entire circuit is...
  2. A

    RC Circuit with a Switch: Potential and Charge Analysis

    Homework Statement Two resistors and two uncharged capacitors are arranged as shown above. Then a potential difference of V0 = 12 V is applied across the combination as shown. a. What is the potential at point a with S open? (Let V = 0 at the negative terminal of the battery.) b. What is the...
  3. BarelyOtaku

    Engineering RC circuits, a step skipped in solution

    Homework Statement . [/B] This is problem 7.45 in Fundamental of Electric Circuit 5th edition. 2. Homework Equations First off, I want to go ahead and say that I don't need the solution I already solved it. I went ahead and used Nodal analysis when Vs = 30. I placed a node voltage right...
  4. T

    What happens to the charge on the capacitor as time goes to infinity?

    Homework Statement Homework Equations q(t) = Cε(1-e^(-t/RC)) The Attempt at a Solution for part a) the instant the switch is closed there is no charge on the capacitor so I am pretty sure I can ignore it for this part and use keirchoffs rules to find the currents through each resistor...
  5. minimario

    RC Circuit Current Help: Equations and Attempt at Solution

    Homework Statement Homework Equations ##q = Q(1-e^{\frac{-t}{RC}})## The Attempt at a Solution Don't know where to start...
  6. V

    Time Constant, Maximum Charge, and Current in an RC Circuit

    Homework Statement [/B] With a 12V battery, a 5.00µF capacitor and a 8x105Ω resistor determine the following: a) The time constant of the circuit b) The maximum charge on the capacitor c) The maximum current in the circuit d) The charge on the capacitor as a function of time, q(t) e)...
  7. F

    Need help analyzing an RC circuit

    Homework Statement The circuit contains an ideal battery, two resistors and a capacitor (C= 250 μF).The switch is closed at time t = 0, and the voltage across the capacitor is recorded as a function of time as shown in the graph. Homework Equations time constant = RCThe Attempt at a...
  8. Logan Land

    MHB Voltage Across 10, 20uF Capacitors in RC Circuit

    Two capacitors of value 10, 20 microfarads are connected in series. Then charged with a 100 volt battery. If the capacitors is disconnected from the battery, and then connected to a 2500 ohm resistor, what is the voltage across the capacitors after 1 second?
  9. T

    Analyzing Current in RC Circuits: A Scientific Approach

    Homework Statement In the circuit below the switch is initially open and both capacitors initially uncharged. All resistors have the same value R. a.) Find the current through R2 just after the switch is closed. b.) Find the current through R2 a long time after the switch has been closed. c.)...
  10. L

    Optimizing Camera Flash Performance: The Role of RC Circuits

    Homework Statement Consider the following circuit in a camera flash where a light bulb is in series with a charged capacitor: a) Derive, but do not solve, the governing differential equation for the circuit. (Hint: treat the resistor and the light bulb as a single resistance.) b) Assume...
  11. F

    Graphing Current v. Time for simple 2R1C circuit

    1. Homework Statement The switch is closed. Graph the current in R_{1} 2. Homework Equations V = IR CV = Q 3. The Attempt at a Solution 1) R_{0} can be ignored a) The resistor simply reduces the voltage before any current can be split. b) We're justified, as a result, in...
  12. N

    Engineering Solve Coupled RC Circuit: Find V1(t) & V2(t)

    Homework Statement Hello I want to solve the following circuit, I want to know how the voltage on R1 and R2 develop with time, It start at t=0 when there is no voltage in the circuit ( all V=0). Its a symbolic question, I need to show the equation. V1(t) = ? , V2(t) = ? The current is a DC...
  13. A

    Find resistance of resistor in RC circuit

    Homework Statement Find the resistance of resistor R7 when the switch is turned on so that the power of that resistor is maximum in the circuit. The voltage of the capacitor before the switch is turned on is Vc=200V. Homework Equations Thevenin's theorem The Attempt at a Solution I...
  14. L

    How Does Closing a Switch Affect RC Circuit Components?

    Homework Statement See the imgur link http://i.imgur.com/yZsyoHx.png Homework Equations See the imgur link The Attempt at a Solution I am just reading a problem in the textbook and am not solving the problem Basically I am looking for a good explanation of how current behaves and components...
  15. Captain1024

    Obtain Expression For Voltage Across Capacitor

    Homework Statement A voltage source given by ##v_s(t)=25cos(2\pi\times10^3t-30^\circ)## is connected to a series RC load. If R = 1MOhm and C = 200pF, obtain an expression for ##v_c(t)##, the voltage across the capacitor. Answer known to be: ##v_c(t)=15.57cos(2\pi\times10^3t-81.5^\circ)##...
  16. A

    Engineering Creating a Bode Plot for a Series RC High Pass Filter

    Homework Statement Make a blode plot of a series RC high pass filter (log(gain) vs. f)... Homework Equations log(Gain)=log(Vout/Vin) I'm pretty sure the "Gain" is just the transfer function, for a highpass it should be the V_in = Vsupply, and V_out = V_capacitor. The Attempt at a Solution I...
  17. ghost313

    Turning a PART of electrical into mechanical energy

    So I am awere of everything in electromagnetism in physics,but lately I am enjoying in creating RC cars.But I only got to making a car going only forward,how can i make him turn?How could I transform only a part of the electrical energy into mechanical so that my RC car can turn left and right...
  18. E

    RLC Circuit Frequencies Help

    Homework Statement In each of the four circuits shown, an AC input voltage, ##V_0 cos(\omega t)## is applied on the left and the output voltage is measured on the right. Treat the input frequency as a...
  19. E

    Charge & Current in a Circuit: V, R, C, & t

    Homework Statement There is a circuit with a battery of voltage V and resistor R, then splits into two branches one with a capacitor C, and one with a resistor 2R. The answers for the questions can only depend on R, C, V, and t. When a switch only allows current to flow through the capacitor...
  20. A

    Potential of Point A to Point B in Difficult RC Circuit

    Find the potential of point a with respect to point b in the figure (Fighttps://s.yimg.com/hd/answers/i/1ffe0f8aeaf145679cde38f7812b1c7f_A.png?a=answers&mr=0&x=1413484693&s=0943630e47eb74ae023909f7d39f74e3 ure 1) . If points a and b are connected by a wire with negligible resistance, find the...
  21. A

    Determining Horizontal Sweep for RC Circuit Time Constant - Physics Lab

    Consider a series RC circuit with an R = 3.0 Ω and a capacitance of 12 µF being charged to a voltage of 5.0 V. (Note, you will not include units in your answers.) If you wished the charging of this capacitor to have a vertical displacement of 4.0 DIV from 0 charge to fully charged, what value...
  22. N

    RC circuit, expression for voltage

    Homework Statement Assume you have a fully charged capacitor with initial condition V(0) = V_0 connected in series to two resistors R_1 and R_2. Derive an expression for the voltage over the capacitor with respect to time. Homework Equations 1. Kirchhoff's voltage law \sum_n V_n = 0 2. Ohm's...
  23. Fyr554

    Alternating currents circuits

    Homework Statement part 1 Consider the circuit of figure G, where R1=20 ohms R2=10 ohms X1=37.7 ohms X2=-53.1 ohms. Compute the current and the phase angle between the current and the applied voltage. In the figure R1 is in series with X1 and R2 and X2 are in series. R1 and X1 are in parallel...
  24. S

    RC Circuit with alternating voltage source

    Homework Statement I'm supposed to find the current in a circuit with a voltage source, capacitor, and resistor in series. The voltage source is described by V=V0ejwt. Here, j is the complex number j2=-1, and i is the current Homework Equations I=C*dv/dt The Attempt at a Solution I have...
  25. B

    Dissipated energy in RC circuit

    Hi there. I'm trying to evaluate the energy dissipated due to Joule effect on a resistor within an RC circuit (R, C, and battery in series), with the capacitor initially uncharged. Till now I just came up with the formula for the current flowing in the circuit i(t) = e^{-\frac{t}{RC}}, resulting...
  26. A

    RC Circuit: How Does Current Flow?

    Homework Statement My question is very simple and perhaps it has an obvious answer. So, if we have a simple RC circuit with and EMF battery, a resistance and a capacitor, when the capacitor is charging, electrons leave the negative terminal of the battery and accumulate on one of the...
  27. STEMucator

    Basic RC Circuit Homework: Calculate Time Constant & Charge Decay

    Homework Statement The emf of the battery in the given circuit is ##\epsilon = 8.0 V##. (a) Calculate the time constant of the circuit. (b) Calculate the charge in Coulombs when the capacitor is fully charged. (c) If the effective capacitor is allowed to discharge through the effective...
  28. R

    Engineering Calculate the Resistance of the RC circuit so that LED just stays on

    In a simple series circuit there is a 12V supply battery, 12μ6 F capacitor, a Resistor, and a 2v drop LED with an imax of 30mA. frequency is 10Hz Calculate the resistance of the resistor so that the LED just stays on. Homework Equations Resistance of Capacitor Xc = 1/2∏fC P=VI V=IR...
  29. I

    Engineering Help in Finding the v(t) of the RC circuit?

    Homework Statement This is the Problem with the answer: Homework Equations V=RI V_{c}(t)=V_{0}e^{-t/(RC)} The Attempt at a Solution Actually, this is a topic about laplace transform. I tried to solve the problem using the formula. @t<0 I=40/(3+8) = 40/11 A V @ 3 ohms =...
  30. dwn

    Engineering Solving for Unknown Current in RC Circuit: Understanding Capacitor Behavior

    Homework Statement Image The Attempt at a Solution I know how to solve for a and c. a: 300V / (300Ω) = 1 A c: 120V / (200Ω) = 0.6 A what I don't understand is how they solved for B (0.6A), considering the current is 3A provided by the capacitor. I initially tried to...
  31. K

    First order RC Circuit Table problem

    Homework Statement Hi I got this problem and have to fill out this table. Homework Equations node analysis time constant = RC ic(t)= C dVc(t)/dt The Attempt at a Solution I got few answers which i worked it out. i (0-) = 0 Vc(0-) = 1.84 Vr(0-) = i (0-) *...
  32. A

    Calculating Capacitance in an RC Circuit: A Mentor's Guide

    [Mentor's note: this thread does not use the standard homework-help template because it originated in a non-homework forum. It was moved here instead of being deleted because it had already gotten significant help.] "A capacitor is being charged from a battery and through a resistor of 20...
  33. G

    Mutual Inductance of RC Circuit on a Small Coil

    Homework Statement My textbook has two problems, based on the same premises, but the solutions manual solves each of them differently, so I was wondering why? Here are the two problems... 1. In the circuit shown in Fig. P29.49, the capacitor has capacitance C = 20μF and is initially charged...
  34. T

    Find Current in RC Circuit w/ V=Vo Sin(ωt)

    Hello there, I'm not sure if my solution is correct for \hat{I}_{C} Homework Statement In the given circuit, calculate the current in each circuit element given that V = V_{o}sin(ωt) R, L and C are given. http://imgur.com/yO3flg8 Homework Equations Z = R + jX (j^{2} = -1) X_{L} = jωL X_{C} =...
  35. E

    Engineering RC circuit time constants and coefficients

    Homework Statement I have got this circuit: I have to find coefficients k1 and k2, and time constants T1 and T2. Actually, we can see that T1 =R1*C1 and T2=R2*C2, but is it possible in this circuit or it's just theoretically time constants? I'm not sure, but as there is no amplifier in...
  36. T

    RC circuit, discharge with digital signal from FPGA

    Hi all, my task is to measure the charge time of an RC circuit with a counter using FPGA, once the cap is charged, i must discharge it again for next input. Idea is to discharge it with a signal from FPGA, but what sort of circuit would allow this without discharging the cap prematurely...
  37. N

    Induced EMF in metal loop near RC circuit

    Homework Statement (Challenge Problem 80, Ch33) A rectangular metal loop with 0.050 ohms resistance is placed next to one wire of the RC circuit shown in the below figure. The capacitor is charged to 20 V with the polarity shown, then the switch is closed at t = 0s...
  38. B

    Engineering Derivation of Source-Free RC circuit

    Homework Statement Hi, If there is a series combination of a resistor and an initially charged capacitor, I know that the decay of the voltage is given by the equation v(t) = Ae^(-t/RC) where V(0) = A = V0. But i am unsure of how to get to this equations. Homework Equations If I assume...
  39. U

    Finding current and charge in a RC circuit.

    Homework Statement A resistor with resistance R and a capacitor with capacitance C are connected in series to a direct current battery ε. find the current and charge on the circuit as function of time. it looks more like a review of differential equations, so I'm not really sure if I...
  40. A

    Engineering Finding R and C from a parallel RC circuit

    Homework Statement A RC parallel circuit with an impedance of Z = 105000 Ω ∠ -27 and frequency of 50 Hz. Homework Equations I need to find out what the R and C values using the information given. The Attempt at a Solution I know the impedance for a parallel RC can be calculated...
  41. N

    RC Circuit current through capacitor question

    Homework Statement Specifically #13 only. Homework Equations Same image as above. The Attempt at a Solution Loop equations 10 - 500,000* i1 - 500,000 * i2 - 500,000 * i3 = 0 10 - 500,000* i1 - q/ 5 * 10^-6 - 500,000 * i3 = 0 Junction equations i1 = i2 + dq/dt i1 = i3 Solving for i1 in...
  42. gfd43tg

    Engineering RC circuit with rectangular pulse

    Homework Statement Consider the circuit below. If the source υs represents a 12-V, 100-ms-long rectangular pulse that starts at t = 0 and the element values are R1 = 6 kΩ, R2 = 2 kΩ, R3 = 4 kΩ, and C = 15 μF, determine the voltage response υ(t) for t ≥ 0. Homework Equations The...
  43. gfd43tg

    Engineering Solve RC Circuit Switch w/ Vs=10V, R1=20kΩ, R2=100kΩ, C1=6μF, C2=12μF

    Homework Statement 2. The switch in the circuit below had been closed for a long time before it was opened at t = 0. Given that Vs = 10 V, R1 = 20 kΩ, R2 = 100 kΩ, C1 = 6 μF, and C2 = 12 μF, determine i(t) for t ≥ 0. Homework Equations The Attempt at a Solution For this problem...
  44. M

    Solve RC Circuit Question: Time Constant & Current

    Homework Statement Switch S has been open for a long time. It is then suddenly closed. Determine the time constant (a) before the switch is closed and (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 time. Homework...
  45. majormaaz

    How to Calculate Energy Dissipated in an RC Circuit?

    Homework Statement The switch in the figure below has been in position a for a very long time. It is suddenly flipped to position b for 1.65 ms, then back to a. How much energy is dissipated by the 50 Ω resistor? (Assume = 65 V.) Homework Equations ΔVloop = 0 Volts Q/V = C V = IR...
  46. majormaaz

    Solving RC Circuit Problem Homework

    Homework Statement Consider the circuit in the figure below, in which V = 85 V, R = 40 , and the switch has been closed for a very long time. (a) What's the charge on the capacitor? (b) The switch is opened at t = 0 s. At what time has the charge on the capacitor decreased to 10% of...
  47. T

    Engineering Calculating voltage and current of RC Circuit

    Homework Statement Attached. Homework Equations The Attempt at a Solution Attached. I am looking at the circuit at t<0. I need to calculate v(0) but I'm not sure how to apply nodal analysis when you have a capacitor in the circuit. Do capacitors follow ohm's law?
  48. T

    Understanding Oscilloscopes: How Can We Use Them to Measure RC Circuits?

    The biggest problem is that I have no knowledge about the math for oscilliscopes. This is a post lab but all we actually did was push a few buttons to record measurements, we did not go into any detail about the methods, just what an oscilliscope was supposed to measure. Homework Statement...
  49. H

    What is the voltage across the capacitor?

    Homework Statement The figure shows the circuit of a flashing lamp.There is a current through the lamp (see the photo) only when the potential difference across it reaches the breakdown voltage VL; the capacitance DIScharges completely through the lamp. (a)A lamp has breakdown voltage...
  50. H

    RC circuit question: In vs. Out phase angle

    In an RC circuit, the phase angle between the input and output voltages (not current and voltage) seems to be proportional to the amplitude of the output voltage. That is, as the phase angle between input and output goes to plus or minus 90 degrees, the output voltage goes to 0. Why is that?
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