Rc Definition and 643 Threads

  1. H

    Driving an LED through RC circuit(RC time constant)

    Hi, i am trying to design a circuit, where i am trying to light up an LED long enough based on my pulse signal. Here is what i am trying to do. a 10us pulse(every second) --->74HCT04 buffer---> (RC circuit)----> LED. since this is a 10us pulse, i want to make sure to light up the led for...
  2. P

    How Do Parallel Resistors and Capacitors Affect RC Circuit Half-Life?

    Hey Everyone, I have a question regarding physics. Say you're given an RC circuit with two identical capictors and two identical resistors and that the two resistors are connected in parallel and the two capacitors are connected in parallel and both are used in the circuit. How can you...
  3. W

    Rb and Rc problems in electroweak theoy

    What's the Rb and Rc problems in electroweak theoy?
  4. 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...
  5. 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...
  6. B

    Solving the Minimum RC Network for Open-Circuit Voltage Gain of 2

    This is not homework, but a question I have posed for myself. In a linear, passive, 3-terminal RC network for sinusoidal voltage input how many resistors and capacitors are required to give an open-circuit voltage gain of 2? I've found some very complicated networks, but I'd like to find...
  7. 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...
  8. 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
  9. 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...
  10. S

    How Does Gauss' Law Apply to Electric Fields and Capacitance Calculations?

    Guass' law and RC 1. Homework Statement 1. Find the potential due to a charged line of charge density lambda. the point of interest is on the axis of the line, and a distance afrom the near end of the lone . the line os of length b. the potential is: k lambda ln(a+b)/a). 2 Show that for...
  11. 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...
  12. S

    Wrong Forum: Help with Guass' Law & RC

    help me on these questions please~ srry ~ i posted wrong forum
  13. Z

    RC Circuits: Charge/Discharge Time & Capacitors/Resistances

    In RC circuit, what is the mathematic relationship between the time of charge or dischare and the capacitors ? time of charge or discharge andn the resistances? I know that as the capacitor or the resistance is increased, the time it take to charge is also increase as well. But I am not sure...
  14. 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...
  15. H

    Is the Time to Discharge a Capacitor Always the Same Number of Time Constants?

    Strictly speaking, the equation q=Q_0e^{-t/RC} implies that an infinite amount of time is required to discharge a capacitor completely. Yet for practical purposes, a capacitor may be considered to be fully discharged after a finite length of time. To be specific, consider a capacitor with...
  16. 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...
  17. 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...
  18. A

    Solve RC Circuits: Instantaneous Voltage in Capacitors

    [SOLVED] Help with RC circuits Can someone explain how to find the intantaneous value of voltage in a capacitor at any specific instant in time. I am taking a course in electronics and the textbook isn't really clear on this. I have the equation: -t/T Vc=E(1-e )...
  19. L

    Need calculations for wall climbing RC car

    I am trying to imitate the Airhog zero gravity climber one of these http://www.gmhummer.com/forums/showthread.php?t=111 can someone please help me regarding derieving equations for the suction pressure required and regarding selection of motors for driving suction fans. the toy...
  20. C

    Engineering Experimenting with RC Combinations: Finding C & R Values

    This is an experiment Ill have to write up later, unfortunately I was out for 2 weeks of lectures due to illness. This is the experiment; Find the values of capacitance C and resistance R in a series combination, given he following apparatus; 1. the unknown RC combination (both in the same...
  21. S

    Engineering How Does Closing a Switch Affect the Voltage Across an RC Circuit?

    Homework Statement The switch has been open for a vary long time, and is then at time T=0 closed. Determine the voltage V0(t) for t>0 Homework Equations voltage from a discharging capacitor is V*e^(-t/RC) Where V is the voltage stored in the capacitor, R is the resistance and C is the...
  22. 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) =...
  23. J

    IR Lap Counter for RC Cars - Need Help

    I've seen the designs using the 555 timer as the base and making a 2 led IR emitter. These examples use 5v and only two leds to send the 40k signal. http://www.reconnsworld.com/ir_ultrasonic_555timer40khzir.html I would like to modify this design to run off 12v and use 8 infrared leds. I...
  24. 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...
  25. S

    RC Circuits and maximum voltage calculation

    [SOLVED] RC Circuits Homework Statement 1. I have two questions in regards to RC circuits, the first one is how to calculate the maximum voltage across a capacitor, knowing the charge on a battery and the capacitance. 2. The other question involves this circuit where the potential...
  26. M

    Using Constant Sources in RC Circuits: Parallel & Series

    Why does a constant current source need to be used in a parallel RC circuit? Why does a Constant Voltage source need to be used in a Series RC circuit?
  27. C

    A Few RC Circuits/Electricity Problems

    Homework Statement 1. What electric field strength is needed to create a 5.0 A current in a 2.0-mm-diameter iron wire? 2. You need to design a 1.0 A fuse that "blows" if the current exceeds 1.0 A. The fuse material in your stockroom melts at a current density of 500 A/cm^2. What diameter...
  28. P

    What is the time constant in an RC Circuit?

    RC Circuits! A capacitor in a single-loop RC circuit is charged to 63 % of its final voltage in 1.5 s. Find (a) the time constant for the circuit and (b) the percentage of the circuit's final voltage after 3.5 s. Given that V/Vo = 63%, t = 1.5 sec , Time constant =τ Now...
  29. M

    AC RC finding voltages before/after switch

    The problem is in bold and my logic/answers/questions are below. Please check my logic and any help with my uncertainties would be...well, helpful. thx The switch has been in position 1 for a long time. Determine the voltage drop Vc(0) and V0(0-). Since it has been a long time the capacitor...
  30. S

    RC Circuits: Voltage as a function of time

    Homework Statement There is an RC circuit with a 6 V battery, a 100 Ohm resistor, and 2.0 microFarad capacitor. At time t = 0, the switch is closed. While this happens, an ammeter measures the current through the resistor. At t = 0.000139 s the ammeter finds that 0.030 A is flowing through...
  31. 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}}...
  32. E

    RC & RL Circuits: Capacitor Current Source & Inductor Voltage Source?

    Does the capacitor acts as a current source and the inductor acts as the voltage source in the RC and RL circuits respectively? If so why does the capacitor not act as a voltage source and inductor not act as a current source? Thankyou
  33. J

    Does the R vs. tau Graph in RC Circuits Always Pass Through the Origin?

    Homework Statement In an RC circuit, should a graph of R vs. tau necessarily go through the origin? What does a non-zero intercept indicate? Homework Equations The Attempt at a Solution My graphs look like they go through the origin, and from the equation tau = RC, I would...
  34. J

    RC Circuits - Why Does the Graph of R vs. tau Pass Through the Origin?

    I'm working on an RC circuit lab and I can't figure out if my graph of R vs. tau is supposed to go through the origin. According to the equation tau = RC, it seems like the graph definitely should pass through the origin. However, given the definition of tau as the time constant equal to the...
  35. L

    How does an RC phase shifter work?

    Hi guys, Here's the link to a RC phase shifter -...
  36. 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?
  37. 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)...
  38. 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...
  39. D

    Mastering RC Voltage Calculation for Chopped/Full-Wave Rectified AC Waveforms

    I am trying to figure out how to come up with an equation to calculate the voltage across a capacitor for an RC circuit that is supplied by a chopped / full-wave rectified ac waveform shown below. The shaded portion is the actual input signal to the RC circuit. anybody have any ideas ?
  40. 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...
  41. 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...
  42. 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...
  43. 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...
  44. G

    Mercury Sable RC steering help

    hey, i need some help with a project i am working on. what i am trying to do is take a full size car and turn it into a RC car. however, inorder to keep the car street legal, i need to keep all the controls operable by a person. i am using only off the shelf parts and servos that you can...
  45. D

    Rc Hovercraft Race @ Shaastra 2007,india

    Hi friends SHAASTRA 2007 (IIT MADRAS,INDIA) brings you an opportunity to earn a lot of cash and become famous . Participate in FIRE n ICE event where you have to make a small hovercraft and compete with others. For more information look at the link below...
  46. 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...
  47. 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...
  48. B

    Build RC Kit Yourself: Easy Steps for Assembling & Controlling

    hi.. i m new here.. quite recently, i hav turned my attention to radio controls. i also built one but blew it up coz of messy power supply. what i want to know is that if i buy a complete radio control kit from a hobby shop, ll i be able to assmble it myself n ll there be any manuals for...
  49. 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! ) 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...
  50. M

    Do RC Circuits Stop Current Flow Through Capacitors Initially?

    While working on an example in my Circuit Analysis textbook, I came upon the following circuit: A 9v battery is connected to a resistor R1 (this is the left loop of the circuit). It is also connected to a resistor R2 and a capacitor C1 that are in series (that is the right loop). The authors...
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