Rc Definition and 643 Threads

rc (for "run commands") is the command line interpreter for Version 10 Unix and Plan 9 from Bell Labs operating systems. It resembles the Bourne shell, but its syntax is somewhat simpler. It was created by Tom Duff, who is better known for an unusual C programming language construct ("Duff's device").A port of the original rc to Unix is part of Plan 9 from User Space. A rewrite of rc for Unix-like operating systems by Byron Rakitzis is also available but includes some incompatible changes.
Rc uses C-like control structures instead of the original Bourne shell's ALGOL-like structures, except that it uses an if not construct instead of else, and has a Bourne-like for loop to iterate over lists. In rc, all variables are lists of strings, which eliminates the need for constructs like "$@". Variables are not re-split when expanded. The language is described in Duff's paper.

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  1. 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...
  2. 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...
  3. 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...
  4. P

    A book for designing RC aircraft

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  5. I

    RC vs RL Filters: Power Loss & Which is Better?

    this guy on youtube said "if you try pushing more than a few miliamps through an RC filter then you get significant power loss" and that therefore the RL filter was more preferable. @ 2:40: i thought L & C components don't dissipate any power, so what's the difference between running the same...
  6. A

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

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  7. R

    Design, Manufacture and Machining of Carbon composites for RC planes

    Hi Guys Recently I have started a new hobby into RC planes. What I have noticed is extensive use of Carbon composites weight yet sturdy structures. Now the problem is that these structures seem to be cut (milling/drilling/laser cutting/water jet cutting) from a sheet (or laminates) of carbon...
  8. C

    MHB Calculating Height of RC Glider from Ground and Air Measurements

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  9. A

    Potential of Point A to Point B in Difficult RC Circuit

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  10. A

    Determining Horizontal Sweep for RC Circuit Time Constant - Physics Lab

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  11. N

    RC circuit, expression for voltage

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  12. S

    RC Circuit with alternating voltage source

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  13. B

    Dissipated energy in RC circuit

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  14. C

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  15. P

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  16. X

    Dielectric Polarization Components in Ideal RC and C circuits

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  17. A

    Network -- RC network with sources

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  18. N

    Phase Differences in of voltage in RC and LR circuits

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  19. Austine-J5

    Making the body of a RC helicopter from balsa wood

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  20. A

    RC Circuit: How Does Current Flow?

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  21. STEMucator

    Basic RC Circuit Homework: Calculate Time Constant & Charge Decay

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  22. Tesladude

    Combining modules to transmit video signal for RC car

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  23. S

    RC time Circuit; charge of capacitor as a function of time derivation

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  24. 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...
  25. M

    Understanding RC Capacitor Discharge Theory

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  26. I

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

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  27. dwn

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

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  28. J

    Help understanding rc circuits?

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  29. 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-) *...
  30. dwn

    Parallel RC with current source

    Homework Statement See images In the first image, I made a circuit with the switch closed and then two when the switch is opened. The bottom circuit is the Thev transform. Homework Equations The Attempt at a Solution Let me first explain my understanding of the circuit. Prior to t = 0, the...
  31. 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...
  32. I

    Exploring the Relationship Between Complex Power and RL and RC Circuits

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  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. P

    Understanding Phasor Analysis in RC Circuits

    I understand that the voltage phasor for a resistor is in phase with the current phasor in a simple ac circuit consisting of only an AC voltage source and the resistor. I understand that the voltage phasor for a capacitor is pi/2 radians behind the current phasor for an AC circuit consisting...
  38. P

    Understanding Phasor Relationships in RC Circuits

    I understand that the voltage phasor for a resistor is in phase with the current phasor in a simple ac circuit consisting of only an AC voltage source and the resistor. I understand that the voltage phasor for a capacitor is pi/2 radians behind the current phasor for an AC circuit consisting...
  39. V

    A couple of questions about RC and RL Circuits

    Question 1: why is the voltage of a capacitor as t goes to infinity equal to the voltage source? This question has been answered. The steady state voltage is not simply equal to the voltage source. Question 2: So that does that mean voltage and current are always 90 degrees out of phase...
  40. 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...
  41. 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...
  42. A

    Engineering RC parallel circuit, find the value of R and C

    Homework Statement The circuit is a Parallel RC Z= 105KΩ∠-27 and Frequency is 50 Hz. I was given the following information and hints. 1/z = 1/R + jwc I need to find the common denominator of 1/R + jwc, Invert it to find z and simplify Z into one real and one imaginary part...
  43. 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...
  44. 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...
  45. 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...
  46. 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...
  47. 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...
  48. 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...
  49. 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...
  50. 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...
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