Questions tagged [electrical-engineering]
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447
questions
0
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1answer
36 views
What does this symbol represent in circuits?
I was watching a YouTube video on the superposition theorem and came across a symbol :
The symbol on the right .
He says it's a current source , Is that all it is ? Is there a name to this so that I ...
-1
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0answers
29 views
Can any two elements in the circuit be labelled as series or parallel? If not, how can I find voltages and currents? [migrated]
This is a voltage amplifier circuit I want to build and curious about the series parallel connections so to understand the working of each element. My understanding of the circuit is:
6.8k ohm ...
0
votes
2answers
41 views
Why do we use high resistance wire in potentiometer?
I was recently learning about potentiometer and , my teacher told thta potentiometer wire has very high resistance , but if potentiometer wire has very high resistance , wont the current skip ...
0
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0answers
10 views
Is it possible for the voltage drop across the depletion region in a diode to be more than the actual biasing voltage?
We know that there will always be a net current in the circuit between the two terminals of the forward biasing voltage source, however small the forward biasing voltage is (see @jonk 's comment).
...
11
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14answers
3k views
How do electrical devices limit the current flow from a socket?
How does a home appliance limit the amount of current that flows
through it?
Are there some resistors set up in series in order to cut
down the current flow before it actually reaches the device?
...
0
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0answers
46 views
Why does the value of shunt resistor need to be very high for solar cell's greater efficiency? [closed]
Here is the correct answer from another stack website: electronics.stackexchange.com/a/570917/288858
In the circuit equivalent of a solar cell, shunt resistor is described as "The irregular ...
0
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0answers
19 views
Different live and neutral wire terminals on different plugs [closed]
Here is the problem, one of the power cable(1st pic) came with XPG core reactor power supply for my computer, and the other UK plug(2nd pic) is of my Samsung LCD. And as you people can see, both have ...
0
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1answer
19 views
Is the dynamic resistance of a diode due to the narrowing and widening of the depletion zone?
All diodes have a built-in voltage. When a diode is connected under forward or reverse bias, the depletion region either widens or narrows. Obviously, the barrier height also increases or decreases ...
0
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2answers
59 views
Is there a small spark every time a switch is closed to engage a circuit?
Suppose we have a simple circuit with a resistor $R$ connected to a DC voltage source $V_{\text{batt}}$. The circuit can be enabled or disabled by a switch. The dielectric breakdown of air is $E_{\...
0
votes
1answer
24 views
Second-Order Transient Analysis Question [closed]
I am currently stuck on a problem and am unsure on how to solve it. The problem can be seen at the bottom of the post.
I know that for second-order circuits we have to figure out the dampening using α ...
5
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3answers
114 views
How does a transistor work?
Here we can see a Bipolar Junction Transistor (BJT), which has a common base configuration. My instructor recently explained to me its working principle, but I didn't understand his explanation ...
3
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0answers
54 views
Why do I hear static when I plug in my earphones incorrectly?
I use simple earphones which are wired with my laptop. Most of the times I unconsciously plug them in without looking and at times instead of going in the port they touch the laptop body near the port ...
1
vote
1answer
45 views
Can the electric field of an EM wave have a component in the direction of the wave?
I am currently taking a course in electromagnetics and i've stumbled into a problem.
On the Engineering electromagnetics book by sadiku there is a question with the electric field of plane wave as ...
0
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0answers
23 views
Is there a difference between $\rm SiO_2/Si$ and $\rm Si/SiO_2$ when describing the substrate of a field-effect transistors?
I've seen in different papers that the substrate of a FET is SiO2/Si or Si/SiO2 are they describing the same thing or is the order important?
-2
votes
2answers
29 views
Center tap transformer and full wave rectification [closed]
I am trying to understand center tap and full wave rectification and struggling with flow of current. My understanding of center tap is that, voltages will be 180 out of phase for the 2 parts in ...
0
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1answer
46 views
Why are PWR's being build instead of FBR's or LMFBR's?
Why are PWR's still being built in modern times when we have the option to use designs that allow intake of raw uranium without the need for enrichment and allow for recycling of waste material.
I don'...
0
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0answers
56 views
Ramsauer–Townsend effect and Thermal Runaway in Thyratrons / (vacuum tubes)
A few years ago an EE told me that the Townsend effect was involved in thermal runaway within vacuum tubes. I can't seem to find any specifics on this on the internet. Can anyone disprove / verify and ...
2
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2answers
34 views
Why do the two relations of Power in a resistive load $P= I^2 R$ and $P = V^2/R$ (Assume Ideal resistances ) seem contradicting in this situation?
I have seen similar questions in the forum but they fail to be very specific .
I would ask the question from the viewpoint of Problem Solving. Let me put this question from a textbook :
A heater coil ...
5
votes
1answer
380 views
Why does my TV screen stay dust-free while other screens do not?
Recently I bought a pretty cheap flat-screen TV. Screen is IPS, semi-matte. 7 months now, I haven't cleaned it once, no dust at all. The TV works a few hours per day.
I was wondering why it does not ...
0
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0answers
17 views
Do you get correct graph of transfer characteristic, if you take +ive Vds(constant) value instead of -ive. As mostly CNTFETs are p-chnl FET
I'm studying transfer characteristic curve of CNTFET to get value for mobility, S.S, etc. According to my basic background knowledge, NMOS curves lie in the 1st quadrant. While for PMOS they lie in ...
0
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0answers
20 views
Finding current through a branch in a multi-loop circuit
So I have the following circuit and I am supposed to find the current through the middle branch i.e., $I_{2}-I_{3}$.
One way is to use the "loop current method". So using that I formulate ...
1
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0answers
19 views
How do Sources Affect the Linearity of a Circuit
How do voltage/current sources - both dependent and independent - affect the linearity of a circuit?
To apply the superposition theorem, a circuit must be linear. As I understand it, this means that ...
0
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0answers
21 views
What happens when supercapacitor is opened?
what happens to charge of a charged supercapacitor if
the two electrodes are separated apart. do they still hold their charge
if one electrode is discharged and placed back. does it get charged by ...
1
vote
2answers
71 views
How does a Zener Diode work as a voltage stabilizer?
I mean I do have this diagram though and all the stuff about how it works, but I read it and not all of it makes sense. In my notes it says that when the input voltage increases beyond a certain limit ...
1
vote
3answers
94 views
Could light erase a hard drive?
I have been having a theoretical discussion with a colleague at work. He proposed the idea of a laser being able to erase a hard drive.
I know that a hard drive is basically a magnetic disc that can ...
-2
votes
1answer
65 views
Why do they keep the street lights on in the morning? [closed]
I am sure that almost everyone at least once in their lifetime witnessed some street lights being on even in the morning. I wonder why they keep them on in the morning.
Possible Explanations
...
0
votes
1answer
41 views
Voltage drop in a forward biased diode
I'm trying to understand why is there a voltage drop when a diode is in a forward bias. From what I understood the PN-junction creates a potential barrier of about 0.7 V for silicon. Now looking at ...
-1
votes
1answer
54 views
Can electric signals be amplified in a simple circuit? [closed]
If a simple circuit is built with an DC source,an output resistor and an input source (I mean transformer or something through which signals can be passed through this circuit),will it work as an ...
0
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2answers
50 views
How to calculate output resistance for a transistor in common base configuration?
This question more related to my physics practical than a theory question. How do i calculate output resistance if i have the corresponding table for it? I know Ro=...
68
votes
8answers
12k views
Why do fans spin backwards slightly after they (should) stop?
Today, I've decided to observe my PC fan as I shut the computer down. The fan slowly lost angular momentum over time. What I've found really interesting is the fact that the momentum vector change did ...
0
votes
1answer
53 views
What are safe voltage differences to connect 2 batteries in parallel? [closed]
I have a OneWheel electric skateboard with a 58V LiFePO4 battery 130Wh (I believe 14s1p configuration).
There is a method in practice where owners wire EGO LION battery packs (56v 2.5Ah=14s1p, 5Ah=...
0
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1answer
29 views
What is meant by “the current-voltage characteristic was asymmetric and non-ohmic”?
I am currently studying the textbook Light-Emitting Diodes (3rd Edition) by E. Fred Schubert. Chapter 2.1 Compound semiconductors says the following:
In 1874, Karl Ferdinand Braun (1874), a German ...
0
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0answers
13 views
Transfer Lengh Method
Based on the transfer length method (TLM). How in practise would you reduce the contact resistance without changing the sheet resistance of the GaAs? Assuming that the contact resistance can be ...
0
votes
1answer
22 views
Is there a frequency converting amplifier? [closed]
Frequency conversion means output of the amplifier is at a frequency different from that of the input.
2
votes
1answer
48 views
How does a staircase switch work? [closed]
Well, I live in a descent old kind of house with old wiring and connections but a fascinating thing in my house is a 2 way switch (I don't even know if it is called so).
The arrangement is like we ...
0
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0answers
28 views
Changing Voltage
Today I noticed this happening that while my laptop was connected to the charger and there were small voltage fluctuations in my home, I could hear some clear sounds in my earphones (while they were ...
1
vote
1answer
67 views
Reason of saturation region in MOSFET
I can't wrap my head around the circumstance that, somewhen when I increase $ V_{DS} $ the current $ I_{DS} $ will remain constantly. Why is that?
https://www.electronics-tutorials.ws/amplifier/...
0
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0answers
5 views
Max frequency of Helmholtz coils
What is the max frequency achievable with helmholtz coils? And is the magnetic field as strong as a dc electromagnet or does it lose strength with the increase in frequency?
0
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0answers
15 views
How to simply explain correlation between Range, Power and Bandwidth in RF Technologies?
First off, I don't have a great understanding about the physics behind radio frequency technologies. I'm working on a paper evaluating if LoRa infrastructure can help developing communities for a ...
3
votes
1answer
183 views
How is Alternating Current (AC) used in Bipolar Junction Transistor (BJT) without ruining its operation?
In a BJT (Bipolar Junction Transistor), say NPN in common base configuration, we forward bias the Base-Emitter Junction and reverse bias the Base-Collector Junction when using a constant DC supply.
...
0
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0answers
42 views
Oblique incidence over a stratified medium - the transfer matrix is not unitary?
As you've read on the title, my problem is about an oblique incidence problem over a stratified electrical medium.
I've made a quick sketch with the incidence on the first layer. Let's suppose that I ...
2
votes
1answer
64 views
What is causing the acceleration of charges in an ideal TEM transmission line?
As I understand, in an ideal TEM transmission line we can set up the telegrapher equations and solve to show that the line propagates voltage and current waves.
My confusion arises when we recognize ...
1
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0answers
50 views
How point-contact transistor work?
In December 1947 Bardeen, Brattain and Shockey introduced a device which is considered to be the first transistor. This transistor was point-contact device. So, it used metal-semiconductor junctions.
...
0
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1answer
43 views
What is the purpose of a resistor in an OR gate?
What is the purpose of a resistor in an OR gate? Isn't it useless since the gate works even if the resistor is absent?
0
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1answer
19 views
How to connect a computer with something like a little electric car? [closed]
I am a complete beginner and I wondered how to hardware like a controller with a f.e. little electric car. So when I want to program a controller like a ps4 controller so that it can let a little ...
0
votes
1answer
31 views
Parallel grouping of batteries
While studying 'Parallel grouping of batteries with internal resistance' I came across its derivation and found that the equivalent emf to be
Σ(E/r)/(Σ(1/r))
Why didn't we take the equivalent emf as ...
-3
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2answers
138 views
What do capacitors actually do? [closed]
I’ve read answers on Quora about why capacitors are used, and they all pretty much said they store charge, or filter out specific frequencies. But what does that actually mean? What do you achieve by ...
-3
votes
4answers
103 views
What is the purpose of Thévenin's theorem on equivalent circuits? [closed]
What is the purpose of Thévenin's theorem use if there are multiple formulas and theorems available for solving a circuit like KVL, mesh, nodal, etc?
1
vote
1answer
48 views
Signal reflections on conductors at low frequencies where they are not transmission lines
This question might be suited for the Electrical Engineering forum, but I think I might get more scientific explanation/discussion (rather than anecdotal) on this forum.
Is the reflection phenomenon ...
1
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0answers
41 views
What are these white pellet in my speaker used for? [closed]
These are the pics of the speakers in my surface laptop.
What are these white pellets used for.
Similar pellets can be found in many tiny speakers of iPhones and Samsung phones.
