In electrical engineering, electrical impedance is the measure of the opposition that a circuit presents to a current when a voltage is applied.
Quantitatively, the impedance of a two-terminal circuit element is the ratio of the complex representation of the sinusoidal voltage between its terminals, to the complex representation of the current flowing through it. In general, it depends upon the frequency of the sinusoidal voltage.
Impedance extends the concept of resistance to alternating current (AC) circuits, and possesses both magnitude and phase, unlike resistance, which has only magnitude.
Impedance is a complex number, with the same units as resistance, for which the SI unit is the ohm (Ω).
Its symbol is usually Z, and it may be represented by writing its magnitude and phase in the polar form |Z|∠θ. However, cartesian complex number representation is often more powerful for circuit analysis purposes.
The notion of impedance is useful for performing AC analysis of electrical networks, because it allows relating sinusoidal voltages and currents by a simple linear law.
In multiple port networks, the two-terminal definition of impedance is inadequate, but the complex voltages at the ports and the currents flowing through them are still linearly related by the impedance matrix.The reciprocal of impedance is admittance, whose SI unit is the siemens, formerly called mho.
Instruments used to measure the electrical impedance are called impedance analyzers.
I know for a wave moving from left to right, ##\psi_i = Ae^{i(\omega t - k_1x)}##
The first reflection where ##Z_1## is ## R_{12}Ae^{i(\omega t - k_1x)}##
The second reflection. The wave moves from 2 to the limit between 2 and 3 then reflect...
Thus, ##T_{12}R_{23}T_{21} Ae^{i(\omega t - k_1 x...
Here is the internal circuit of the 741 Op-Amp -
Looking at the output stage, the output impedance seems to be the series combination of ##25 \Omega## and ##50 \Omega##, that is ##75 \Omega##. Is this a qualitative explanation enough to justify the output impedance, or am I wrong somewhere and...
I'm not sure if it helps for what I'm looking, but I've calculated the mutual inductance, M, using the equation: M=U2/(ω*I1) = 106.3μH. I don't need the numerical value in particular, I just want to find a way to deduce the formula in order to calculate Z1. Thank you!
My attempt:
p and T allows us to calculate ##Z=402 \frac{kg}{sm^2}## using ## Z=p*\sqrt(\frac{\gamma*M}{R*T})## . The sound intensity level at 10 meters allows us to calculate the intensity at 10 meters to be I=10``````^{-7} W/m^2 using ##50 = 10*log(I/I_0)##. Then, using the formula...
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...
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...
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...
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...
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 constructed...
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...
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...
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...
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...
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).
Homework Equations
P = V^2/R
P = IV
The Attempt at a Solution
I...
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)?
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.
Homework Statement
Compute real power on resistors ## R_1 ## and ## R_2 ## and reactive power on inductor ## L ##. Circuit is powered...
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...
Homework Statement
I am given the following circuit:
and asked to solve for v(t) and i(t)
Homework Equations
The Attempt at a Solution
If this is right, I don't know where to go from here.
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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]
Homework Equations
Find the instantaneous current, and the phasor current.
The Attempt at a Solution
(1.) I first found the frequency of the source:
(314) / (2*pi) ≈...
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.
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...
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...
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
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 =...
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