Time constant Definition and 141 Threads

Electrical Science -- LR Time Constant & Voltage Drops 1. An inductor of negligible resistance and an inductance of 0.2 H is connected in series with a 330 Ω resistor to a 12V d.c. supply. Determine: (a) the time constant of the circuit (b) the voltage drop across the inductor after two...

What is the decay time constant of the waveform? How to determine it from this oscilloscope? The waveforms are in the pictures below:

Homework Statement The short circuit time constant method for determining 3dB point for high pass filter says b1= the sum of short circuit time constant seen by each individual capacitor with the all other capacitor replaced by short circuit. b1 is also = the sum of pole1, pole2...

Homework Statement Signals from sources of different kinds are often very weak and very quick. To minimize the noise risk they're often led through coaxial cables. How long can one [coaxial cable] be if it has the capacitance 80pF / m and resistance 0.04 Ohm/m and you want to transfer noise...

Homework Statement A 3.9kg block hangs from a spring with constant 2160 N/m. The block is pulled down 6.2 cm from the equilibrium position and given an initial velocity of 1.5 m/s back towards equilibrium. The mass and spring are now immersed in water to damp the motion, so that the...

16. As part of a heat-treating process, an alloy-steel billet, initially at 1032°F, is cooled in a 32°F air stream. The temperature history of the billet is shown in the figure at right. What is the time constant τ for the cooling process? I have attached an image of the question. I...

I have a liquid that is stored at pressure. This liquid is then released to a lower pressure where it should become a gas. The problem is how long does it take for the liquid to turn to gas. There must be some delay - even a very small one - but how to calculate it. Example - a jet of...

Homework Statement Here's a link to the circuit: http://tinypic.com/view.php?pic=30js0wp&s=6 Initial current, t, and final current are given. Seeking time constant.Homework Equations I=Io (1-e^(-t/T)) where Io is initial current and T is the time constant. This is an RL circuit right?The...

the attached file is the question I know the time constant after opening the switch but how can i know the time constant when the switch is on? This is NOT the classic initial and AFTER A LONG LONG LONG Time question How can i know the potential of C in t=2s ? What is the equation...

Homework Statement Find the time constant in the following circuit when switch K1 is open. R1 = 100 Ohms R2 = 200 Ohms C1 = 6 micro Farads E1 = 9V Homework Equations T = RC The Attempt at a Solution When the resistors are in series or parallel, I am clear on how to do this...

The image attached is of an underdamped RLC step response. I know that I can find the damped frequency of the response by first finding the period of the wave, and manipulating the period such that I can do 2*pi*f. If I'm looking at this waveform and the only info I know about it is this...

Homework Statement #1. If you needed to store 1 coulomb of charge on a 1000uF capacitor what voltage would be required and what electric field would exist within the capacitor if the plate spacing is .1mm. #2. Using Vc=Vo*e^(-t/RC) show that Vc will be equal to 37% of Vo when (RC) seconds...

Why is time constant form of transfer function in control system better than pole zero form ? If a closed Loop transfer function is given to me how should i find D.C gain ?

Hi! I want to low-pass filter some simulations that I made. The indata to the simulation is built up by several modules and hence at the edges transients will occur. I want to filter these out. The indata in sampled at 20 Hz. How should I set the time constant for the filter? I mean I know...

Homework Statement If you have this RC Circuit (ignore the yellow path of current): http://i.imgur.com/Mi2bj.png When you are calculating time constant=RC, what would you use for R? R1=100 ohms, or Req=300 ohms Homework Equations time constant = RC The Attempt at a Solution...

Homework Statement I know that in a RC DC circuit the time constant is R*C. But what about a RC AC circuit, is it the same time constant? Same goes with RL AC circuit, is the time constant R/L? Thanks!

Hi all, I'm trying to understand the electrical model of a neuron, and I have 2 questions. I'm a little confused about the time constant in this electrical model of neuron recording: The time constant shown is tau = C*(Rm*Rs)/(Rm+Rs), which implies that the resistors are in parallel...

Find the time constant τ for the first order response of the circuit below at t > 0 s. L = 6 H R1 = 8 Ω : R2 = 6 Ω Give your answer to at least two decimal places, in s. I am really struggling on where even to begin with this question. I know that for a simplified circuit t = L/R And...

Homework Statement Find the time constant x(t)=4 e^{-4t} u(t) Homework Equations \tau = \frac{1}{\lambda} The Attempt at a Solution \tau = \frac{1}{\lambda}= \frac{1}{4} = .25 I know the unit step is shifting the start of the decay function to zero, but I'm not sure how or...

Homework Statement In the circuit below, at time t = 0, the switch is closed, causing the capacitors to charge. The voltage across the battery is 12 V. **Image of circuit is attached. A)Calculate the time constant for the RC circuit B)Calculate the time required for the voltage across...

Homework Statement a slab of some insulator with an unknown permittivity ε. To determine ε experimentally I go to the lab and insert the slab in between the plates of a capacitor whose plate spacing exactly matches the width of the slab. I observe that the time constant of exponential...

Hi, Was hoping someone could help me. I have the following RL circuit: 20V input 8.2kohm resistor and 50mH Inductor in series. Determine time constant: I answered with: T = L/R 50mH / 8.2kohm = 6.09 uS Is this correct? The question I am stuck on is: Determine the...

Homework Statement A student is designing an alarm circuit. She wants a time interval between closing a switch and the circuit becoming active. She decides to charge a 2200 mu (x10 -6) F capacitor through a resistor from a 5V supply. The potential difference across the cap. must rise to 4.3 V...

Homework Statement I attached a picture of the RC circuit. The question asks to find the current as a function of time for light bulb 3 (R3). I know that I=Ioet/RC where Io is the initial current that runs through R3 but what about the R in the time constant RC? Is this resistance the total...

Homework Statement A 5 micro farad capacitor is in series with a resistor, a switch, and a 12VDC ideal battery. The switch is closed at t=0s. The time constant of the circuit is 4.0s. Determine the value of the resistance R? Homework Equations The Attempt at a Solution From another...

Homework Statement Given this diagram: Picture mirror: http://i.minus.com/1331507225/3XjEXOAlTaoJBoBuQFoJiQ/itFBvAiitDZQc.png With S1 switch closed and S2 switch left open, I am trying to find the time constant Homework Equations I know τ = RC for a basic circuit, but how...

My understanding is that a gas, such as CO2 for example, that interacts with electromagnetic radiation, can only absorb energy at specific frequencies, corresponding to the resonant frequencies of its molecule - equivalently the quantized energy associated with each molecular...

The original question: Notice that they have marked that the correct time constant is T = 2L/R Why is this the correct answer and not L/R? I thought the inductor will only take into consideration one Resistor as in both circuits (switch closed vs open), current will only flow through...

Homework Statement Maximum current: I max = 4.62 * 10^-4 A Time constant of circuit: T = 3.9 secondsHomework Equations T= RC The Attempt at a Solution I'm trying to find the current after 1 time constant. Seems simple enough, the current changes by 63%. So (Imax)-(Imax * 0.63) or...

Homework Statement http://i.imgur.com/wjD8Y.png In the circuit below, V = 6 volts, R = 10 ohms, L = 100 mH. The switch has been open for a long time. Then, at time t = 0, the switch is closed. What is the time constant for the current through the inductor? 2L / R...

Homework Statement A 12.8 micro-F capacitor is connected through a 0.890 M-ohm resistor to a constant potential difference of 60.0 v. Homework Equations q=CE(1-e^(-t/(RC)) i=(E/R)-(q/(RC)) The Attempt at a Solution Compute the charge on the capacitor at the following times...

Hey guys, I recently had a quiz on Circuit is attached in photo below. T(s) = (A)(s/s+20)*(s/s+200) **All values of R in the circuit attached are 2000 ohms. and C1>C2 a. find the mid-band gain A. I do not know how to start this question... Can anyone give me an idea of where...

Homework Statement Quick question. If you were to find the Thevenin's equivalent circuit between the terminals of an inductor, and thus calculated the time constant using Rth, would the time constant be same as if you were to not? Same question for capacitor circuits

Hello. Homework Statement Calculate the time response, Vc(t), of the circuit shown in the attached image. Not use Laplace transforms. Homework Equations I know that tau = RC in a typical RC circuit. In general, Vc(t) = {V0 - Vf}*exp(-t/tau) + Vf, where V0 is initial voltage and Vf is final...

Here is a link to page in a book which contains an example problem: http://imgur.com/OPrlw.jpg" In the book, they work out the natural frequency of a hydraulic cylinder and come out with an answer in rad/sec. This number is then inverted to get a time constant, and the resultant unit is...

Hello, I have a question on a the units of a first order system's time constant. If i have a first order system the basic transfer function will be: K/(tau*s+1) where K is the Gain, and tau is the system's time constant. tau's units, according to what I've learned, are [sec]. but...

Hi, I have read the defination of a time constant on the internet and yet still don't quite understand it. How do I relate it to the following sentece and what does it mean: " The transient energy will have a duration much shorter than the thermal time constant of a bridge wire." ANY...

Two 500μF capacitor are connected in parallel, and then to a 100kW (105W) resistor. The capacitors are momentarily charged using a 1000V D.C. supply. Find: a) The time constant of the circuit. b) The time “t” taken for the capacitor voltage to decay to 630 volts c) The current in the...

Homework Statement What is the time constant of the circuit shown in the figure? Each resistor has resistance R, and each capacitor has capacitance C. Internal resistance of the battery is negligible. See the attached figure. Homework Equations tau=RC The Attempt at a...

See attachment for problem. I am stumped on how to find the rc time constant in this problem. Please help me get started. Thanks.

Homework Statement The top circuit is an example my professor did in class, and how he solved Tao. What I'm concerned with is how he is figure R for L/R The second example is one I found online. How do I figure the R to use? Is it simply the entire thevinin equivalent or a specific...

Homework Statement Two capacitors (c1 = 11 and c2 = 15 μF) are charged in series by a 11 V battery. Find the time constant of the charging circuit. (r = 4 Ω). Homework Equations V=E(1-e^(-t/T)) Where T=Tau=RC, E is the Voltage of the power source, and V is the voltage of the capacitor...

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

Homework Statement I need to find the time constant, tau, Homework Equations WILL EDIT THIS TOMORROW Bleeping FMS giving me major brainache *saddest face ever* A(t) = A_0 times e^-t/tauThe Attempt at a Solution I have had numerous attempts and I just fried my (fibromyalgic) brain out with...

Homework Statement A spring with spring constant 17.0 N/m hangs from the ceiling. A 530 g ball is attached to the spring and allowed to come to rest. It is then pulled down 7.00 cm and released. What is the time constant if the ball's amplitude has decreased to 3.50 cm after 41.0...

The time constant of a thermocouple is to be found by exposing it to a step change. Then the thermocouple and a thermometer are exposed to a ramp function and measurements from each are taken simultaneously. The time constant and its uncertainty for the thermometer are to be found. I...

Homework Statement A battery with emf = 2V is connected to a RC circuit with a 450Ω resistor and an unknown capacitor. After 3.8 milliseconds, the current is 2.2mA. (a) Find the time constant and the capacitance. (b) Now, 2.9 ms after the charging begins, find the current I, the charge...

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...

Why is it generally assumed that time is and has been constant? When a star is described as being 150 million light/years away - how do we know that the time during those years passed at the same rate as time now. Couldn't time have been faster (or slower) in the past?

The exponentially weighted moving average is essentially a first order low pass filter: y(t)=(1-a)*y(t-1) + a*u(t) where y(t) is the present filter output, u(t) is the present filter input, y(t-1) is the filter output at the previous time and a is the smoothing factor or filter parameter...