Rc Definition and 643 Threads

  1. D

    Graph Vout vs Time for RC Circuit Switch Closure

    Homework Statement Sketch a graph of Vout vs time after the switch is closed *See attached diagram* Homework Equations The Attempt at a Solution I am not really sure how to do this, because I don't know if it makes a difference whether or not the resistor is before the...
  2. A

    How Do You Find Frequency in an RC Circuit?

    RC Circuit, Finding Frequency? [Solved] Solved =] Homework Statement Homework Equations Z = [ R2 + (1/wC)2 ]1/2 where Z is impedance, w = (omega) = angular frequency Xc = 1/(wC) w = 2(pi)f (tau) = RC where (tau) is the time constant The Attempt at a Solution I'm more confused than...
  3. D

    Discharging Capacitor in an RC Circuit w/ Battery

    Homework Statement The bit I'm struggling with is to determine the time constant \tau for the referenced circuit after the switch is closed. Constants are given in the image, which can be found at https://www.physicsforums.com/attachment.php?attachmentid=12737&d=1203627574. Homework...
  4. A

    Frequency response of rc coupled amp

    greetings, At high frequency (more than 20kHz) the reactance of capacitor is very small and act as short circuit.this increase the loading of next stage.whats the meaning of increse of loading in next stage? RC coupled two stage amplifier circuit is here-...
  5. E

    What Is the Role of Displacement Current in an RC Circuit?

    In an RC circuit shown below, with the switch closed after a long time, when the capacitor is charging, there is a current across the capacitor given by Initial current x e ^ (-t/RC)... Is this current...the current supplied by capacitor to the rest of circuit, or simply the current across...
  6. E

    Engineering Solving an RC circuit question using Superposition

    Hello, The circuit attached below is from Richard Dorfs Intro to Electric Circuits book. The switch is shut for a long time and opened at t=0. The question asks to find the i(t) across R11, which they use nodal analaysis and find it to be 66.67 - 16.666 e^{-t/120} micro Amps, where 66.67 micro...
  7. E

    Engineering Complex impedance of parallel RC circuit

    In my book (Storey), there's an exercise with a parallel RC circuit, where R = 80 Ohm and C = 30 uF. The answer for the complex impedance is supposed to be 40-j40, however I can't seem to get there! I've showed my working under. Am I doing something wrong, or is the book's answer wrong? (freq...
  8. R

    RC Circuits: Calculating Voltage

    I've been trying to answer the following equation but I just can't get my head around it! 'calculate the time taken 't' for the voltage over capacitor array (Vc) to reach 80% of Vo, in terms of Vo, R, C1 and C2 (caps are in parallel)' I know I need these two equations but I just don't...
  9. T

    Engineering Time Constant RC circuit with dependent source

    Homework Statement Homework Equations T = R*C The Attempt at a Solution I have no idea how to go about this. I know that T=R*C in a RC circuit
  10. A

    Complex conjugate zeros in pure RC ckt

    Hi, Is there a possibility of getting a complex conj zeros in pure RC ckt. we never get complex conj poles but how about complex conj zeros. regards, Asif
  11. S

    Can a Lagrangian be written for a simple RC or RL circuit?

    Hello, is it possible to write a Lagrangian (L) for a simple RC (or RL) circuit? Normally L = kinetic - potential energy, but how would you write this for an RC circuit? thanks!
  12. C

    Engineering How do I calculate Vc and i for an RC circuit with a closed switch?

    Homework Statement The switch in the following circuit has been opened for a very long time and then closes at t=0 (a) Calculate Vc(t) for t>0. (b) Calculate i(t) for t>0. Homework Equations The Attempt at a Solution Here is my attempt of the problem. I have not dealt with a...
  13. M

    What is the Charge on a Capacitor in an RC Circuit?

    Homework Statement An RC circuit is made of a 2.2 kOhm resistor and a 0.001 microF capacitor. The circuit is connected to a 10V source of emf for 5 x 10^-5 s. What is the resulting charge on the capacitor after that? Homework Equations Q(t) = -ECe^(-t/RC) + EC , where E is the emf...
  14. E

    Why is there a 90 degree phase shift in RC filters?

    Hi! Bear with me: When the frequency is low in an RC series circuit and we take the voltage across the capacitor, the capacitors reactance is high and thus most voltage is across it. But when the frequency is high, the reactance goes down, and little to no voltage is dropped across the...
  15. J

    Impedance of a parallel RC circuit?

    Hi there, I have a circuit in which consists of a resistance (rs) in series with parallel combination of capacitor and resistance(rc). I want to calculate value of rs. So i did this by calculating total impedance Ztotal which is V/I and then substracting impedance of parallel rc circuit...
  16. G

    Calculating Time Constant and Effective Resistance for a Parallel RC Circuit

    I am trying obtain some equations for an RC circuit that has a resistor R1 after a battery, which then splits into a capacitor C and a resistor R2 (the circuit closes after this point). When I try to seek help online, the resources are quite unhelpful. I cannot seem for example, obtain any...
  17. B

    Engineering RC circuit analysis using oscilloscopes

    Homework Statement this was a practical examination given to us. [connected to CH1] |----(1.8k ohms)-----| |aaaaaaaaaaaaaaaaaa| |aaaaaaaaaaaaaaaaaa(unknown resistance) [these 2 unknowns are ch2] (~)aaaaaaaaaaaaaaa| |aaaaaaaaaaaaaaaaa(unknown capacitance)...
  18. A

    Engineering Basic RC Circuit but with parallel switch?

    Homework Statement I want to find ix in the circuit below when the switch opens at t=0 after having been closed for a long time.Homework Equations v(t) = v(infinity) + (v(0)-v(infinity))e-t/RC i(t) = C dv(t)/dt ix = isource - i(t) v(t) = voltage across capacitor i(t) = current through...
  19. B

    Engineering Find v(t) for t > 0. RC Circuit Problem

    Homework Statement The switch in the circuit has been closed for a long time, and it opens at t = 0. Find v(t) for T \geq 0. http://img834.imageshack.us/img834/9107/tutorialq2.jpg Homework Equations V(t) = Voe-t/RC \tau = RC The Attempt at a Solution @ T<0 Short Circuit due to capacitor V =...
  20. N

    RC Circuits and Natural Inverse Exponent function

    I was trying to figure out the relation between the equation of a discharging capacitor and the Natural Inverse Exponent function v(t) = Vo*e^(-t/rc) A*e(-Ct)+B I get that A represents the voltage and the C is the inverse of the time constant but i can't figure out what the B stands for
  21. E

    RC Circuit, Need help forming equation.

    Homework Statement The switch has been in position 1 for a long time before moving to position 2 at t=0. Find i(0) for t>0. Image of circuit: http://img215.imageshack.us/img215/9200/circuit3.png Homework Equations KVL First Order Diff Eq The Attempt at a Solution So to start...
  22. J

    Finding Voltage Across A Resistor in a 1st Order RC Circuit

    Homework Statement For the RC Circuit (R = 100 Ohm, C = 100 Micro Farads, and an open switch at t=0), we know that the capacitor is charged to a voltage of 10 V prior to T=0. Find expressions for Vc(t) and Vr(t). Homework Equations Vc(t) = Vi * e(-t/rc)The Attempt at a Solution Vc(t) =...
  23. C

    Turning an RC Aircraft into a Water Bomber: Ideas & Suggestions

    I was wondering how you could turn an RC aircraft out to a water bomber?? I thought of installing a container in the fuselage where water could be filled but can't think of how to get water out. Any suggestions on that or any other ideas of loading the water?
  24. V

    How do you find the time constant in an RC circuit?

    Homework Statement Find the time constantHomework Equations T=RC The Attempt at a Solution I understand the calculation fine. But I was wondering if the resistors are considered to be in parallel with each other even though the second resistor appears to be in parallel only with the...
  25. A

    RC circuit with AC - finding current

    Homework Statement I am given an RC circuit with an alternating current. The circuit contains a capacitor and a resistor in parallel. Part (a) says "Use KCL to find a differential equation for I in terms of V." Part (b) says "For an applied voltage V = Voexp(iwt), find the current I."...
  26. O

    RC circuit and kirchoff's loop rule

    http://www.screencast.com/users/trinhn812/folders/Jing/media/de5edaba-e848-47f5-82b9-bd770b216e95 I need help with Question 27 specifically. The correct answer is A, but I don't understand why. I thought it would be B according to Korkoff's Loop rule of the inner left loop, where current...
  27. S

    Need help finding voltage across a capacitor in an RC circuit?

    1. Homework Statement Find the voltage across a capacitor in an RC Circuit, using [V]_{}[/c] (0) = 1, [V]_{}[/i] n(t)=t. 2. Homework Equations dV/dt = (1/RC)(V)=(1/RC)([V]_{}[/in]) 3. The Attempt at a Solution New to this site: I honestly don't know where to start. Done well in...
  28. S

    RC Circuits (Differential Equations)

    Homework Statement Find the voltage across a capacitor in an RC Circuit, using [V]_{}[/c] (0) = 1, [V]_{}[/i] n(t)=t. Homework Equations dV/dt = (1/RC)(V)=(1/RC)([V]_{}[/in]) The Attempt at a Solution New to this site: I honestly don't know where to start. Done well in Calculus...
  29. H

    Engineering Why is this RC circuit not working?

    Hello all! I am really stuck up here. I have made this circuit and want to measure the voltage across the capacitor. The voltage should gradually increase as the capacitor charges, and then become constant. But, I only get a constant voltage of 6V across the capacitor. Infact, I have to...
  30. A

    Can a UPS be used to power an RC car? Tips from a Computer Eng student

    I want to make an rc electric toy car using a UPS as power suply. It is possible? Some advices please.
  31. P

    Understanding Phase Shift in RC Circuits

    Homework Statement Pls see the attachment. Homework Equations The Attempt at a Solution Obviously I have B and C correct but for a the only thing I can find is tan(phi)=XL-Xc/R This seems to be for a series RLC circuit though and I only have RC. also I know that the current lags...
  32. P

    Any general RC circuit is never underdamped?

    My first post! Question: Is a general RC circuit, with any topology of interconnected R and C elements, never underdamped? This is a bonus question in one of my homeworks. The answers to the earlier questions in the problem indeed show that two example RC circuits are not underdamped. I...
  33. A

    Where Can I Find Resources for Building an RC Heli?

    I wanted to build a RC Heli., can anyone tell me all the parts to make a RC heli(helicopter)..? or a website that contains it..
  34. A

    Where Is Power Dissipated in an RC Circuit?

    When a capacitor is charged by a battery half the power is dissipated as heat and half is stored as potential energy within the field of the capacitor. Similarly a resistor dissipates all power that the battery supplies. Now here's my question: In an RC circuit where is the power dissipated...
  35. D

    Why is V(R) < 0 for discharging in RC circuit?

    Why is V(R) < 0 for discharging in RC circuit?
  36. L

    Building a RC Aircraft with Recovered Control System

    I recently extracted the control system out of a severely damaged RC aircraft (a very simple kit deal). It's got two servos, and a pretty good motor, which works out perfectly for me! I want to build a new aircraft from scratch using the recovered control system. For the fuselage I'm...
  37. P

    Units of RC are the same as time - help

    Homework Statement the title says it all, we are required to show that the units of RC are the same as the units of time. ie. iohm * 1 farad = 1 seconds Need help thanks Homework Equations The Attempt at a Solution
  38. R

    Finding q(t) on a capacitor in an RC circuit

    The following circuit is given: [PLAIN]http://img822.imageshack.us/img822/6369/image2lz.jpg Switch S is closed until the charge q2 on C2 reaches its maximum, then at t=0 the switch is opened. Find q1(t). Using Kirchkoff's rules I found: EMF= (q1)/(C1+I2R I2R= q2/C2 I1= I2+I3 In order to...
  39. G

    RC circuit differential equations

    Hi everyone... I need to solve the differential equations of a RC circuit given a voltage and a current pulse. I have to get this responses: http://i.imagehost.org/view/0340/Respuesta1 I'm using matlab, with runge kutta. I've been solving the equations separately changing the initial...
  40. K

    RC Aircraft Stability: Neutral or Instability?

    For an RC aircraft which i am working on i was thinking about having static stability at the extreme limits of pitching to prevent stalling and further instability, but i was wondering what to have between the limits neutral static stability or static instability. Static instability may help the...
  41. M

    Transient analysis (RC) question problem

    hello friends... i am having following problem in this question. first i don't understand how they have calculated R equivalent=5/6.i think its value should be 25Kohms. will it be different at 1ms and 4ms or same ?\\ i shall be thanks to u . in one picture is the problem n in other...
  42. J

    How Do You Find the Phase Equation of a Lossy Low Pass Filter?

    Homework Statement I'm a bit confused about how to find the phase equation of a lossy low pass filter eg. Homework Equations For a normal low pass filter it's just arctan(wRC) The Attempt at a Solution So I am comparing this by subbing in values and comparing to a bode...
  43. S

    Engineering Question about a paralell-like RC circuit

    Homework Statement I have the circuit that's attached as a .bmp image. I'm asked to find the initial current that passes trough the battery (V=60 V) knowing that the capacitor is initially charged with charge q_{0}=0.1 C. The resistances are R_1=R_2=R_3=1 Ohm and C=1/1000 F. Homework...
  44. 1

    Violation of Kirchhoff's Laws for a Coherent RC Circuit.

    Thank you ZapperZ for introducing these new peer-review papers. This one is of particular interest to me. I believe I may have some insight into this issue. In the normally constructed RC circuits using discrete components, the reactions of the individual components to signal frequency...
  45. J

    RC circuit - Capacitor discharge

    When a capacitor discharges, the potential difference between its plates and the resistor's terminals is the same. Hence, \frac{Q}{C}=R \frac{dq}{dt} Solving this equation we get q(t)= Q_{0} exp \frac{t}{RC} Obviously, this isn't the solution. It is actually q(t)= Q_0 exp...
  46. H

    Calculating time constant in RC circuit

    I know that T = RC I've tried different combinations of R (not really sure what Req to take) but none of them worked. Any one can show me the right way ?
  47. L

    Charging and Discharging RC circuit

    Homework Statement I'm confused by the interpretation of the charging and discharging formulas: Charging: Q= Qo (1-e^-t/RC) Discharging: Q=Qoe^(-t/RC) Like for Qo, like apparently its the max charge, so does that mean at the very end of charging? Initially, i thought that Qo meant that the...
  48. L

    Finding Rate of Energy Loss in an RC Discharge Circuit

    Homework Statement In an RC discharge circuit, R= 2.5 X10^4 ohms and C=40 microfarad. The initial potential difference across C is 25 V. Find the rate at which energy is being lost by C at 0.5 seconds. Homework Equations The Attempt at a Solution Like in this case, I probably have...
  49. L

    RC circuit and a microfarad capacitor

    Homework Statement A 10.0 microfarad capacitor is charged by a 10.0 V battery through a resistance R. The capacitor reaches a potential difference of 4.00 V in a time interval of 3.00 s after charging begins. Find R. Homework Equations The Attempt at a Solution So basically i got...
  50. P

    Finding Resistance of Voltmeter in RC Circuit

    The question asks to derive the equation you need to find the resistance of a voltmeter in a simple RC circuit like the one shown here: http://people.ee.duke.edu/~cec/final/node32.html But R2 in the link is actually a capacitor in my circuit. The equations in the lab journal are Vc=q/C...
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