# impedance

1. ### Engineering Circuit input impedance with ground in an OP Amp circuit

I've been given the following circuit and have been asked to find the input impedance and the impedance between the input terminal and ground. I've never encountered an operational amplifier configured like this. I know that the voltages at the - and + terminals of the op amp are ideally equal...
2. ### Impedance of RF Connectors

I am just a bit confused as to how impedance is matched with RF connectors such as type-N or BNC connectors. I know Coaxial cabling and RF connectors come in common impedance ratings like 50 or 75 ohm but how is this all matched properly? For example many people have told me that when using...
3. ### I The role of capillaries in a dilution refrigerator

I've been trying to understand how dilution refrigerators work and inbetween intermediate steps, between different temperature points, I see capillaries here and there under the name of impedances. After some googling, I somewhat convinced myself that it's to build up pressure before and after...

Hi all, I am currently working on a project where the output/load consists of both a variable inductance and variable resistance, whilst the circuit driving this load is a class E radio frequency (RF) power amplifier with low resistance but relatively high/medium reactance (attempting to design...
5. ### I Effect of impedance changes less than a wavelength

I am interested to know what is the impact of various length scales of impedance changes on wave propagation. From undergraduate physics (a few years ago for me) I roughly remember how to derive reflection and transmission coefficients for a wave travelling from one medium to another with a...
6. ### Input impedance of a "Ladder" transmission line

1. Homework Statement My electronics&physics lecture notes contain the following side note: ___ "A ladder transmission line comprises an alternating sequence of segments of two different transmission lines both of length $l$ with characteristic impedance $Z1$ and $Z2$. If the line is...
7. ### I Short Circuiting the Secondary of a Transformer/Self Impedence

Thank you for reading my post. I was watching the video this video on transformers and saw an amazing demo: From 4:00-5:20 the guy does an experiment where he has a simple transformer circuit set up: On the primary side of the transformer he has an AC power supply, and a lightbulb. On the...
8. ### Wall thickness vs frequency... sound isolation

When sound hits a wall,part of it gets reflected and part of it gets transmitted due to acoustic impedance difference between solid and air. My problem,and point of this question is that having material or gas impedance number is completly useless unless we know the frequency and wall...
9. ### I Stray/Parasitic Capacitance - Impacts phase velocity?

Hey everyone, I'm trying to measure the stray capacitance in a circuit comprised of an rf signal generator, an oscilloscope, a coaxial cable (short-circuited) and some capacitors. I measured the resonant frequencies of the coaxil cable for varying values of capacity (0pF to 850pF) between 4MHz...
10. ### Acoustic impedance in Materials

Acoustic impedance of material is defined by density multiply by the velocity of waves within the base material. My question is if i have a tubular or hollow part with a base material, does this count as a reduction of density compared to the base material of the tube or hollow part. Would the...
11. ### Why does having a high input impedance and low output impeda

1. Homework Statement Say you connect Circuit A with low output impedance to circuit B with high input impedance. Why does this cause minimal voltage drop compared to connecting them the other way around (high output to low input). 2. Homework Equations P = V^2/R P = IV 3. The Attempt at a...
12. ### How should I calculate conductivity

Hello, I would like to ask if I have this data from impedance spectroscopy: frequency, Z(im), Z(Real), how should I calculate conductivity ? Should I use R(im) or R(re)?
13. ### Engineering Finding Phase Difference in an RC circuit

1. Homework Statement 2. Homework Equations $V = ZI$ $Z_R = R$ $Z_C = -\frac{j}{\omega C}$ $Z = \sqrt{R^2 + (\frac{1}{\omega C})^2}$ $P_{av} = \frac{1}{2}V_m I_m cos(\phi)$ $\phi = arctan(\frac{-1/\omega C}{R})$ $\Delta \phi = \phi _1 -\phi _2$ 3. The Attempt at a Solution...
14. ### Engineering RL Circuit Power Computation

I'm having some problems understanding why my computation deviates from solutions. I thank in advance to anyone who can give me some tips where I've gone wrong. 1. Homework Statement Compute real power on resistors $R_1$ and $R_2$ and reactive power on inductor $L$. Circuit is...
15. ### Is there microscopic version of general Ohm's law of V=IZ?

Hello. Resistive Ohm's law is famously known as V = IR. We can derive its microscopic version as being followed. V = El, where E and l are, respectively, an electric field and a resistive load length over which a voltage drop V is developed. I = JS, J and S are a current density and a...
16. ### Current and voltage with inductors and capacitors

1. Homework Statement I am given the following circuit: and asked to solve for v(t) and i(t) 2. Homework Equations 3. The Attempt at a Solution If this is right, I don't know where to go from here.
17. ### RMS Current through RLC combination ciruit

1. 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? 2. Homework Equations V = IR Z = √(R^2 + X^2) 3. The Attempt at a Solution...
18. ### I 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?
19. ### 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...
20. ### Discrete Differential Amplifier

1. Homework Statement Calculating the open loop output Impedance at 1kHz and the open loop differential gain 3. 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...
21. ### The battery equivalent internal impedance equation

1. 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: 2. Homework Equations Values...
22. ### 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...
23. ### Solving voltage divider involving capacitors

1. 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. 2. Homework Equations I know that 1/ZV = 1/ZV1 + 1/ZV2 + 1/ZCV VV = ZV / (ZV + ZCCV) * VC 3. The Attempt at a Solution 1/ZV = 1/ZV1 + 1/ZV2 + 1/ZCV...
24. ### 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...
25. ### 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...
26. ### Engineering RLC 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...
27. ### 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
28. ### 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...
29. ### Engineering Calculating values of impedance in a series/parallel circuit

1. 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...
30. ### Engineering Instantaneous Current in single phase circuit

1. Homework Statement SOURCE: v(t) = (311)cos(314t) [v] IN SERIES WITH: R = (0.3) [Ω] L = j(0.7) [Ω] "load" = 2.5 + j(1.0) [Ω] 2. Homework Equations Find the instantaneous current, and the phasor current. 3. The Attempt at a Solution (1.) I first found the frequency of the source: (314)...