Impedance Definition and 507 Threads

  1. G

    Impedance matching concerns equivalent impedance of circuit?

    Hello. Please look at the attached image first. There are two circuits A and B which have individual electrical components a and b. Components a and b are electrically and directly connected by the red lines. Impedances of individual components a and b are not matched, however, equivalent...
  2. Cocoleia

    Current and voltage with inductors and capacitors

    Homework Statement I am given the following circuit: and asked to solve for v(t) and i(t) Homework EquationsThe Attempt at a Solution If this is right, I don't know where to go from here.
  3. E

    Calculating Impedance for a Source: Solution Attempt

    Homework Statement Find the impedance as seen by the source. Homework EquationsThe Attempt at a Solution -j2||j1 = 2i Z = 2-j1+j2+(1^2)/(j2+2+j2) Ztotal = 2.1+0.8i Is this correct?
  4. V

    I What is the approximate impedance of an RF plasma "antenna"?

    I've searched high and low for data regarding this from scientific papers to books and I cannot find anything in regards to the approximate impedance to excite a vacuum vessel to plasma state. In particular I want to built a RF Plasma cleaning chamber, however, I am not sure how to design the...
  5. I

    How to Simplify Backward Impedance Matching Equations?

    Homework Statement https://scontent-lax3-1.xx.fbcdn.net/v/t34.0-12/14804959_10155526179417281_80533891_n.png?oh=649ee14155ac558b21c6553f003e418b&oe=5809EAA0 Homework EquationsThe Attempt at a Solution 1) I determined the input impedance of the first transmission line (Zin1). 2) I calculated...
  6. Aimen

    Impedance of circuit (R, L in series. C in parallel)

    Hello. Homework Statement What is the impedance of a circuit in which resistor and inductor are connected in series with each other, and a capacitor is in parallel with them? How should I sum the voltages in order to find the impedance? 2. Homework Equations V = IZ IZ = VR + VC + VL ? The...
  7. notnerd

    Find the impedance and ω for (R and L in series, & C in || )

    Homework Statement Find the impedance (Z) of the circuit in the shown figure (R and L in series, and C in parallel with them). A circuit is said to be in resonance if Z is real, find ω in terms of R, L, and C? Homework Equations VR= RIeiωt VL= LiωIeiωt VC= (Ieiωt)/(iωc) What I mean by I is I...
  8. K

    RMS Current through RLC combination ciruit

    Homework Statement Referencing the attached picture: a) Show that the RMS current in the 1 kΩ resistor is 6.5mA. b) If the AC voltage source was replaced by a battery, what would the current in the resistor be? Homework Equations V = IR Z = √(R^2 + X^2) The Attempt at a Solution To begin, I...
  9. J

    Input Impedance of off center fed dipoles

    My name is Jackson Richter. I am retired from Rockwell-Collins and worked in the engineering lab for 31 years. Since my retirement my interested have peaked in radio communications. Especially in antenna design. Thanks to anyone here that would give me a little more insight with my...
  10. L

    Transmission line impedance question

    I am a bit confused on source impedance and Tline impedance, when both are equal. Let's say source impedance is 50 ohms and Tline imepdance is also 50 ohms. Why does the incident wave divide between the source impedance and tline impedance. The impedance is same, so reflection co-efficient...
  11. Kfir Dolev

    Combine capacitors and inductors to be frequency independent

    Is it possible to combine (possibly infinite) capacitors and inductors to get a total impedance which is independent of frequency. If so, how?
  12. kostoglotov

    Will an infinite impedance cause no phase shift?

    Homework Statement imgur link: http://i.imgur.com/0Zc8nQe.png Homework Equations Y-Delta transformations The Attempt at a Solution Since it's a proof, I can't check the answer in the back. What I did: I transformed the three impedances in their delta config to a Y config, and my TI89...
  13. CopyOfA

    Modeling and Measuring an Electromagnetic Coil in ANSYS HFSS

    I've been attempting to model a simple electromagnetic coil using HFSS, and have so far been unsuccessful. I have no problems constructing the coil; this is a simple geometry problem. I have a wire of a known geometry with insulation surrounding the wire, then a construct a helical path and then...
  14. O

    Discrete Differential Amplifier

    Homework Statement Calculating the open loop output Impedance at 1kHz and the open loop differential gain The Attempt at a Solution Here is the approach. INPUT STAGE: Q111 and Q112 Av1 = Rtot/2re, where Rtot is the total resistance of R117 and the input resistance of Q78 which is Rin. So...
  15. cnh1995

    Rotor and negative sequence impedance of alternator

    When an alternator is supplied with a 3-phase voltage and its rotor is rotated in opposite direction to that of the stator rmf, the ratio phase voltage/phase current is the negative sequence impedance of the alternator. My understanding of this is as follows: When rotor is rotated in opposite...
  16. I

    Impedance matching hydrophones and DAQs

    Hello, I'm confused about the concept of impedance matching in regards with hydrophones and DAQs. If the input impedance to an ADC channel on a DAQ is very high, would I need whatever's being fed into it (hydrophone) to also need a high impedance? Or would it need a low impedance? I've tried...
  17. Planobilly

    How does probe attenuation affect input impedance on a scope

    I assume the 10X setting to be the most useful with audio work. Comments?? My oscilloscope has 1M ohm input impedance when set at 10X as stated above. What is the likely impedance at 1X ? The manual indicates the above chart is based on the probe being set at 10X. As I am dealing with DC...
  18. C

    What is the Acoustic Impedance of Wool?

    Homework Statement I need this to find the the reflective coefficient and multiply this by 100 to find the percentage of original energy reflected back however i cannot find the acoustic impedance of wool no matter how hard i try. Homework Equations Im using the reflective coefficient formula...
  19. M

    The battery equivalent internal impedance equation

    Homework Statement Hello, long story short: I need to create a model of Li-Ion battery and I'm stuck on calculating the battery equivalent internal impedance. The thing is, I don't know the equation or even how to make one. However, I have a circuit drawing: Homework Equations Values in...
  20. jrmiranda

    Why does impedance in lumped circuits depend on position?

    I was wondering, at high frequency circuits, when the lumped circuit model must be used, why does impedance depends on the position in the wire? By the way, it's my very first post here =D
  21. S

    Engineering Impedance angle in RL and RC circuits

    Homework Statement This isn't so much of a problem itself but I found it interesting that on the All About Circuits website, two of the questions give a phase angle for impedance as opposite the angle of current. I understand the current is 90 degrees out of phase with voltage in both RL and RC...
  22. ReidMerrill

    How Do You Calculate Impedance in an RLC Circuit at 3000 Hz?

    Homework Statement A series RLC circuit consists of a 60.0 Ω resistor, a 2.30 mH inductor, and a 690 nF capacitor. It is connected to an oscillator with a peak voltage of5.80 V . Part A Determine the impedance at frequency 3000 Hz. Part B Determine the peak current at frequency 3000 Hz. Part C...
  23. J

    Impedance of a 5kW generator (synchronous single phase)

    Hi everyone! As a Belgian student electrical engineering, I am going to Peru this summer with Humasol vzw, a development organisation that works with engineering students. Our job is to build a hydro turbine next to a small river to provide a little community with electricity. Also part of our...
  24. W

    Solving voltage divider involving capacitors

    Homework Statement Given ZV1 = ZV2 = 100Ω, ZCCV = ZCV = 2000/j = -2000j, and VV/VC = 0.04789. I'm trying to get the given VV/VC result. Homework Equations I know that 1/ZV = 1/ZV1 + 1/ZV2 + 1/ZCV VV = ZV / (ZV + ZCCV) * VC The Attempt at a Solution 1/ZV = 1/ZV1 + 1/ZV2 + 1/ZCV = 1/100 +...
  25. P

    Impedance of capacitor and inductors

    I do not understand how to solve capacitors and inductors with impedance. I do not even know what it is that they use it to solve for. My understanding is that the define the source as a sinusoid using the complex exponential form, and that all voltages and amperage are now also complex...
  26. Enochfoul

    Impedance Question Homework: Solving for Z with Complex Numbers

    Homework Statement Hi would somebody please be able to check to see if my workings look good? Homework Equations 1/Z=1/Z1+1/Z2 IF Z1 = 3 + J2 and Z2 = 1 - j3, calcualte Z giving your answer in the form r(cosθ + jin son θ) where θ is in radians The Attempt at a Solution Attached as a...
  27. Hyo X

    Reduce Amplifier Drift when load is near input impedance

    I built a voltage amplifier based on the AD625 instrumentation amplifier. This chip has a 1 G-Ohm input impedance. When the load has a resistance of 100 kOhm, output drift is negligible. When the load has a resistance of 100 MOhm, output drift is significant and not acceptable. Are there any...
  28. P

    Complex Impedance of a voltage source and 2 resistors

    Homework Statement A real voltage source can be expressed as an ideal voltage source that is in series with a resistor that represents the inner resistance of the voltage source. This voltage source is a EMF and it is also in series with another resistor. Suppose both the EMF resistor...
  29. Y

    Impedance calculator for asymmetric differential stripline

    Hi Anyone know of an online asymmetric differential stripline impedance calculator? I already have the Saturn pcb design tool kit. I just want to find a second one to cross check the result. My experience is I have seen two calculators gave different results. Thanks
  30. S

    What happens to the wave impedance of free space at ω=0?

    For a plane wave traveling in free space we know from Maxwell's equations that: Z= E/H=√μ0/ε0 = 377Ω The meaning of the wave impedance is that if we have an electric field oscillating with amplitude E0 in a medium (in this case the vacuum) a magnetic field will be induced with amplitude E0/Z...
  31. AnonymousPT

    Field Effect Transistor - High Input Impedance

    I know FET offers a very high input impedance..but what's the reason behind it? Is it due to the reverse voltage applied at gate with respect to the source which makes the P-N junction reversed biased? If that the case, what happens when there is no voltage applied at gate?
  32. C

    Understanding Norton Current and Impedance in Point A to B Circuit

    Homework Statement Find Norton current and impedance between points A and B. Homework EquationsThe Attempt at a Solution I really don't have idea how to find impedance when points A and B are positioned like that in the diagram. And if let's say I found the impedance , when trying to look for...
  33. C

    What Is the Maximum Power on an Impedance Z?

    Homework Statement Find the maximum power on a impedance Z. Homework EquationsThe Attempt at a Solution I got as Thevenin impedance Zt=4+j4 and Ut= 32 V, but since my solution for power is wrong, something is wrong with either impedance or voltage (or both). If point A is above Z, and point B...
  34. uzi kiko

    Impedance matching and tuning of RF coil

    Hi everybody. I am trying to understand the concept of impedance matching and tuning of RF coil. As far as I understand there are 2 stages: At the first stage I should match the coil to the source (Let's say with L network method) and the second stage is to tune coil to the desirable frequency...
  35. uzi kiko

    Impedance matching and tuning RF coil

    Hi everybody. I am trying to understand the concept of impedance matching and tuning of RF coil. As far as I understand there are 2 stages: At the first stage I should match the coil to the source (Let's say with L network method) and the second stage is to tune coil to the desirable...
  36. G

    Output Impedance of an Inverting Op Amp

    Homework Statement Hello, I just came across a design problem based on an inverting op amp. The requirement output values are -25G and not greater than 1kOhm output impedance. With inputs 1V p-t-p and 75Ohms input impedance Choosing values for the gain seem fairly easy, but how these values...
  37. Domenico94

    Understanding Equivalent Impedance in a Bridge Circuit | Homework Help

    Homework Statement Hi everyone, I'm just having a little trouble with equivalent resistance in a bridge, in the image I attached. The textbook says that the way to solve this is to put R3 and ZL2 in series, that series is in parallel to the short circuit in diagonal, and then at the end we...
  38. T

    Meaning of zero/infinite impedance

    I was calculating the impedance of a capacitor and inductor of ## 1 \mu {\text F}## and ##1 {\text H}## respectively, at ##1000 \frac {\text rad}{\text s}## in both series and parallel configurations. I found the impedance to be 0 and infinity in the two cases, which is correct. But now I'm just...
  39. I

    Acoustic impedance water surface in partially filled tank

    Hello guys, Consider a partially filled tank with water where the acoustic field can be described by the Helmholtz equation. The boundary condition at the water surface would be \frac{∂p}{∂\vec{n}} = -j\rho_0\omega\frac{p}{Z} where Z is the impedance of the water surface. What would be...
  40. I

    Surface impedance water layer in partially filled cavities

    Hello guys! I have to model the acouctic field within partially filled cavities. So consider a rectangular or cylindrical cavity that is partially filled with water. I would like to model the water layer as a sound absorbing wall by prescribing it as a surface impedance boundary condition...
  41. R

    Engineering Correct application of Circuit Impedance and Circuit Current

    Im trying to complete a worked example and just looking for validation whether what I am doing is correct. I am given the following: Supply: 230V ∠0° R: 100Ω ∠0° χL: j10Ω ∠90° χC: -j40Ω ∠-90° I struggled a bit with the j operator and using the polar/rectangular functions but this is what I've...
  42. T

    Impedance matching between two 50 ohm cables through a joint

    Hi, I'm in a bind trying to determine how to handle impedance matching through a joint of copper wire sandwiched between two 50-ohm coaxial cables (the joint is an interface between atmosphere and a UHV system). There is a signal pulse with a rise time of 2 ns coming through one of the coaxial...
  43. N

    CMOS to Microstrip Impedance Matching

    I need to somehow take the output of a CMOS IC and transmit that signal over a 50 Ohm Microstrip line. The output impedance of the CMOS IC is about 15 megaohms. I see a lot of examples for going from 75 ohms to 50 ohms or similar but nothing on something of this magnitude. Any ideas? CMOS...
  44. R

    How do you calculate a thickness dependant impedance to a so

    ... sound wave? I need a simple method to calculate the impedance between water and silicone as ultrasound passes through them i.e. how much of the signal is reflected at the water silicone boundary. The problem is I am having trouble finding the required equations, Wiki is extremely...
  45. T

    Engineering Find Frequency for Zero Reactance in AC Circuit

    The question is: The voltage source in the above circuit is a sinusoidal AC source with constant amplitude and constant phase shift but an adjustable frequency. Calculate the frequency ω at which the phasor current I...
  46. T

    Double check apparent power definition

    Hey just to make sure, can we say apparent power S = V^2 / Z for a complex impedance Z? And do we have to worry about conjugates at all? Cheers
  47. neduet

    Earthing and Grounding or Protective Earthing

    1 “earthing” for bonding of equipment and circuits to common plant earth electrode potential, 2 “protective earthing (PE)” when this bonding is required for personal safety provisions 3 “grounding” for interference suppressing bonding of screens, sys- tems with ground level 4. low-impedance...
  48. R

    Engineering Calculating values of impedance in a series/parallel circuit

    Homework Statement Hello everyone, I have recently come under some stress from not being able to get these answers correct. I need to calculate these values: Zeq IT XL2 XL1 VR1 VR2 VL1 VL2 For this series circuit: And these values: Zeq IT XL2 XL1 IR1 IR2 IL1 IL2 For this parallel circuit...
  49. P

    Acoustic horns and impedance matching

    I found a fast solenoid valve lying around (~1ms rise time) so I thought it would be fun to hook up to a compressed air line and use to generate some really loud bass. I hooked it up to a function generator and air supply only to find that it was disappointingly quiet (well not quiet, but...
  50. S

    Series Coupling Capacitor as Impedance Inverter of Resonator

    Hi, I have been having this question for a long while. From Pozar's book (Microwave Engineering), on page 336, when he was solving for the resonance response and the Q factor for a Lamba/2 resonator terminated by an open circuit, and coupled to the feed line through a series capacitor, at some...
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