Impedance Definition and 488 Threads

Homework Statement [/B] I need to find the total impedance for this circuit below. No values are given so I just need to write out an equation. Homework EquationsThe Attempt at a Solution I'm having a hard time deciding what is in parallel/series. I took a guess and came up with: ( R...

Homework Statement A series RLC circuit is connected to a 60 Hz AC source which produces an amplitude of εmax=20 V. The circuit element values are R= 20 Ω, L= 20 mH, C= 150 μF. Calculate the total impedance of the circuit. Homework Equations Xc=1/ωC XL=ωL Z=√(R^2 +(XL-Xc)^2) tan φ = (XL-Xc)/R...

Homework Statement [/B] Calculate impedance of the node shown in this feedback circuit with Blackman and the Vtest/ Itest method. Homework Equations [/B] Zin (with feedback) = Zin(with feedback circuit disabled) * (1-RRshort)/(1-RRopen) RR = return ratio In this form blackman theorem to us...

Question in relation to audio. I read online that a low impedance system is less susceptible to EMI and RFI than high impedance. How? I thought that high impedance = high resistance, therefore higher resistance to EMI and RFI. Would love to be updated with the explanation. Thanks.

Question: A 1-microF capacitor and a 1-kOhm resistor are connected in parallel, and this parallel combination is connected in series with a 200-mH inductor. Find the equivalent impedance of the connection at w=1 krad/s. Relevant Equations: Z=R for a resistor, Z=jwl for an inductor, and...

Hello. The attached image is L impedance matching network, use for impedance matching between source and load impedance. The calculation shows that in this circuit, load impedance Rp sees whole impedance (equivalent impedance) of the source impedance and reactive components as matched to...

Hello I'm now studying transmission line theory. I got to know how impedance matching between characteristic impedance of transmission line and electrical load is important to achieve maximum power transfer and minimize power reflection which causes danger for the system. But the textbook...

The following show the idea how a Thevenin equivalent source is used to replace the primary circuit of transformer. https://www.dropbox.com/s/0kaazx1d1srgirz/reflectedsource.jpg?dl=0 https://www.dropbox.com/s/0kaazx1d1srgirz/reflectedsource.jpg?dl=0 In textbook it is commonly stated that the...

I have a question about complex reflection and transmission coefficients. For example, I am modeling a wave in air (medium 1) ## \varepsilon = \varepsilon_0 ## reflecting on, and transmitted to, a medium 2 with ## \varepsilon = \varepsilon' -j \varepsilon'' ## If the wave would have traveled...

Homework Statement design a common-emitter amplifier with an output impedance of 4.7kOhms and again of-10 using a transistor with a beta=200 powered by a 12V DC supply. Homework Equations v=ir The Attempt at a Solution ------------------------------------------------------ rest of the...

THIS IS NOT A HW/COURSEWORK QUESTION! I am simply revising for an exam and am trying to better understand the behavior of the stripline as shown in the file attached. What would be the effect on the characteristic impedance, as W/b/epsilon_r/t increases (each separately)?

Hi all, I am wondering if there is a need for impedance matching to charge a battery from the source? Thank you

Homework Statement Homework Equations Law of Superposition I=V/R The Attempt at a Solution I am reducing the circuit. i) By law of Superposition, short circuit V2 100 ohms on the leftmost branch and 50 ohms on the rightmost branch, both are in parallel so 100*80/(100+80)=44.4 ohms seen by...

Homework Statement Given the relationships: Xpu = MVAbase / MVAfault Xpu = ( MVAbase / MVArated ) * ( X% / 100 ) MVAfault = sqrt(3) * V * Ifault Xohms = [ V / sqrt(3) ] * Ifault Homework Equations Show that: Xpu = [ MVAbase / V^2 ] * Xohms The Attempt at a Solution No matter how I...

Homework Statement Homework Equations V=IZ The Attempt at a Solution So my plan is as follows: Find the current through the 1 ohm resistor, multiplying this by the combined impedance of the capacitor & 1 ohm resistor. Now I know the voltage across the unkown impedance Z. Subtract this...

Homework Statement The current in a series circuit of R=5 ohms and L=30 mH lags the applied voltage by 80 degrees. Determine the source frequency and impedance. (Ans: Z=5+j28.4 , f=150.4 Hz) Homework EquationsThe Attempt at a Solution Current in the inductor, IL = Vm/wL*sin(wt-80) Current...

Hi, I was just wondering why, when the acoustic impedance mismatch is so high between two boundaries at an interface, most of the ultrasound is reflected back. I was just wondering why this happens which I can't seem to find much of an answer to. The only thing I can think of is refraction and...

Homework Statement Determine the input resistance using blackmans impedance formula. I know all the ressisor values, and transistor data. Homework Equations [/B] Blackmans impedance formula The Attempt at a Solution Our teacher has given us a example on how to find the open loop gain, but...

Homework Statement In magnetic resonance imaging (MRI), we use radiofrequency (RF) coils to transmit oscillating magnetic fields into the patient. The coils are essentially series RLC antennas and must be tuned to resonate at the characteristic frequency of the experiment (called the Larmor...

i am a 3rd year Mech batch doing my dissertation on developing an inductive sensor to determine wear in brake discs. As you know it works by inducing eddy currents into the disc and the are monitored by measuring the impedance of the coil. i am really struggling with understanding the impedance...

Homework Statement Consider a circuit with a capacitor C in series an inductor of inductance L. Explain what happens when ω2LC=1, without calculations, using your knowledge and intuition. Homework Equations 1/Z = 1/impedance = 1/(iωL) +1/(iωC) i is pure imaginary. The Attempt at a Solution...

Homework Statement (a) A transmission line has a length, ℓ, of 0.4λ. Determine the phase change, βℓ, that occurs down the line. (b) A 50Ω lossless transmission line of length 0.4λ is terminated in a load of (40 + j30) Ω. Determine, using the equation given below, the input impedance to the...

Homework Statement In the circuit shown the 120V, 60Hz source supplies the ideal load shown through an ideal 2:1 transformer. What steady state current would you expect to read on the rms ammeter shown (please find the picture attached)? Homework Equations Zeq = (1/Z1+ 1/Z2)^-1 Z1 =...

Dear all! I have a question about the impedance characteristics in the distance relay used for transmission line protection. I understand that in the first quadrant we have a inductive load and in the fourth quadrant we have a capacitive load. I, however, do not understand what we measure in...

May I pose a question concerning impedance matching and Smith diagrams?

Audible hearing range for humans: Roughly 20-20khz That's almost 20,000 values to choose from:eek: Other/additional info: I don't understand your question BeautifulLight. If your circuit is operating at 2khz, then calculate for 2khz. Simple. Well, this is for a speaker. Human speech can make a...

Why don't we just connect a sine wave generator in series with a DMM and the coil, set the amplitude Δv0 to a given value on a scope, measure the RMS current I on the DMM and use Z = 0.707Δv0/I?

We have looked fairly extensively at waves on a string without anything on them, however there is a portion in my notes about an infinite string with a mass in the middle. Essentially the setup is that x=0 we have a mass. Here the waveform on each side must be equal as the string is continuous...

I recently attended a seminar, which said impedance increases with temperature, which results in timing delays in digital circuits. I don't understand how increase in impedance results in delay.

Hi, I am working on a PCB that requires controlled trace impedance. I figured out width of the traces and layer stack thickness. How would I verify trace impedance once I get my PCB boards? What equipment do I need?

Hi All, I am measuring the impedance response of a piezoelectric component. It has a unique impedance response having a resonance portion (low impedance ~10-30ohmns) and large impedance (100k-200kohmns) within a 2kHz bandwidth. See the webpage for a figure showing the impedance behavior. The...

Please see attached On line S=0.5*V*I why is the minus sign removed from in front of the "I" angle. 25.38 specifically. Could is be a typo? http://imgur.com/eUmEovo

From the research I have done, I believe I have fully grasped the concept of impedance -- my initial problem being is that I suspected it had to do a lot with lenz' law, but no sources clearly stated one way or another. What I need is verification that I am correct or to be corrected...

Hi, If I have two brances, branch 1 and branch 2 which are in parallel and each branch has a resistance and inductance, to calculate the equivalent series resistance and inductance, can I calculate the resistance and inductance separately e.g. Req = R1*R2/R1+R2 (and same for X), or do I have...

Homework Statement This is one part of a wider question, I'm only posting the part I'm having trouble with. $$ \begin{align} \text{Given an impedance network } B &= \frac{Z_1 \parallel Z_3}{Z_2 + Z_1 \parallel Z_3} \\ \text{show that: } \frac{1}{B} &= 1 + \frac{R_2}{R_1} + j\frac{\omega CR_2}{1...

Homework Statement Find ##i(t)## in the following circuit: Homework Equations ##Z = \frac{V}{I} \Rightarrow I = \frac{V}{Z}## The Attempt at a Solution I've solved this, but I'm wondering why my answer is different than the book's answer. The book lists the answer as ##i(t) = 3.88...

Hey all, When a Bipolar Junction Transistor is "OFF" (i.e., Vb = 0), what are typical Emitter-Collector impedances? We are using a switching BJT as a switch for a stepper motor, however, we have just realized that the impedance is rather low when the transistor is off (470 Ohms). I would have...

Homework Statement Calculate the impedance Zin[/B] Homework EquationsThe Attempt at a Solution [/B] I cut VDD and the DC current source at the top. Put in test DC voltage VTest - 10* ITest = VGS (because voltage "after" the resistor = the voltage at the gate and the drain, and source is...

Homework Statement I am calculating matching impedances for a source and its load using 2 different L-network topologies. One is: source-parallel-to-C, load-series-to-L and the other is: source-parallel-to-L, load-series-to-C. I go through all the calculations and notice that...

sufficient enough to redirect/shield against ultrasound 1MHz being directed through the air. i know a vacuum would. What I'm questioning is if you had 2 layers of different materials stacked on top of each other what could prevent the ultrasound from reaching the 2nd layer assuming the 1st layer...

Homework Statement know that the frequency is10hz and 4.7kΩ resistor calculating the impedance in kΩ i spend half hour on this and still have no idea what to do ,tell me the formula or the step thanks Homework Equations The Attempt at a Solution

I was working on trying to find the short circuit current rating of a 120 volt panel fed from a 7.5KVA transformer. Using P=IV you get 7.5KVA=120 * I I = 62.5 Amps. Then I believe you divide that current by the impedance of the transformer. .03 is the impedance in this case in the...

Hi, I was reading Charles Steinmetz "Theory and Calculation of Alternating Current Phenomenon" and on page 89 (can be found online easily) Steinmetz defines impedance as: Z = R - jX, but see it commonly defined as R + jX. I read on wikipedia there are two impedance equations for capacitive...

Hi, Since the primary side of a transformer is a closed circuit (like the cubical adapter for the iphone charger), it would make sense that even if my iphone wasn't plugged into the secondary, the primary would still draw power. I know this is the case for at least some adapters, because i...

Hi, I have read Steinmetz books and he has a very good example of OC phenomenon that is nothing like AC case. There are certain conditions under which an OC transformer has zero impedance. Also, on his chapter of long transmission lines, he says quarter wave resonance using abrupt pulses can...

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Hello everybody, Three conductors are being simulated in Maxwell with a peak current. From Maxwell I extract the impedance matrix (3x3 matrix) of the three conductors. Conductors are placed on top of each other so there will be mutual inductances and resistances. The documentation on the...

I am working on impedance measurements of close-wound electromagnetic coils. I am using an Agilent LCR meter to measure the impedance of these coils over a frequency range of 20Hz-2MHz. When I perform the measurements, I get impedance magnitude and phase angle in degrees. I would like to...

Hello to experts! What is impedance inversion in quarter wave transformer? I need definition not a concept, not explanation, not description. But a precise and point definition. Thank you very much.

I have solved it (: Homework Statement Ir=Impedance of a resistor = 330 Ic=Impedance of a capacitor=318 V= Sinusoidal Voltage = 240 V (RMS) is applied across the series combination. calculate the resulting current. Homework Equations Not sure The Attempt at a Solution I am really not sure how...