Questions tagged [electrical-engineering]

The engineering discipline concerned with the study, design and application of equipment, devices and systems which use electricity, electronics, and electromagnetism.

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Charge moving in an electric field and magnetic field? [closed]

lets say I have an electron moving towards an oppositely charged plate. Perpendicular to the electrical force vector, exists a magnetic field. How would I calculate the force on the electron? Like ...
Jais's user avatar
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Collector-base biasing in pnp transitor as amplifier [closed]

For a pnp transistor in common emmiter configuration used as an amplifier, what is the collector-base junction biasing? I found out on internet that it is forward biased thus both the junctions are ...
Amit Rai's user avatar
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Resistance in series also slows current down so why is resistance connected in parallel in galvanometer ammeter and not in series?

When we convert a galvanometer into an ammeter we connect the resistance in parallel, the only reason we connect a resistance in parallel with galvanometer is so less current passes and the flow of ...
Mathematition_From_Wallmart's user avatar
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For intrinsic semiconductors, is the gap Energy equals $E_c-E_v$ or $E_c+E_v$?

So I have a problem with the intrinsic Fermi Level because by definition it is in the middle of the gap energy, and knowing that Eg=(Ec-Ev), we should have Ei=(Ec-Ev)/2. But when we follow the ...
anass bakour's user avatar
2 votes
1 answer
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How a switching mixer works in this example circuit?

I am reading about lock-in amplifiers and came across this example circuit of a mixer: You have one sinusoidal input signal $e_1$ with a phase $\phi_1$ and the local oscillator has a square-wave ...
NeonGabu's user avatar
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2 answers
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EM wave emission from earphone wires due to varying current signal

if we listen to some audio signal on a wired earphone, then does the wire of the earphone act as a transmitter antenna to emit the audio signal as radio waves even though its strength might be ...
sab's user avatar
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How is gradient magnetic field generated in MRI scanner, considering 0 divergence

During the phase and frequency encoding process of MRI scanner, gradient field with a gradient is applied along the direction to change kx and ky of spins at different spatial location. I am confused ...
Yan's user avatar
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When forming an n channel in an N mosfet, do the pn junctions of the drain-substrate and source-substrate parts disappear?

When forming an n channel in an N mosfet, do the pn junctions of the drain-substrate and source-substrate parts disappear? Here's what I expected: When gate voltage (higher than threshold voltage) ...
KHJ's user avatar
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2 answers
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What is the "closed circuit" of a bug swatter racket?

There are bug swatter racket that can kill fruit flies, mosquitos, or flies, if the insect touches the metal mesh. However, when I look at the construction of the device, the metal mesh is all one ...
Stefanie Gauss's user avatar
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Is the direction of base current always constant in a BJT transistor?

Is the direction of base current always constant in a BJT transistor? Excluding the transistor breakdown state, is the direction of the base current always the same in the four modes: active mode, cut-...
KHJ's user avatar
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Voltage across the diode?

Why the voltage across an ideal pn junction diode remains 0.7 volts, even when the applied voltage exceeds 0.7 volts? Shouldn't it be the applied voltage minus the 0.7 V?
Alex's user avatar
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What can cause a spot above my WiFi router's antenna? [closed]

Lately a weird dark spot has appeared right above the antenna of my wifi router. It wasn't there before. I have tried to wipe it and it got a little bit brighter but I don't think it's dust. My guess ...
Szil_K's user avatar
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How does an antenna work?

I'm looking for a model of an antenna that would explain how it works an in particular where the values of impedance like 36.5 ohms come from. I've tried looking but everything i found was overly ...
Jan Szwyngel's user avatar
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Mesh current analysis but with variable resistors [closed]

I can't seem to be able to introduce V0 here! Here was my working out, using 3 mesh and 4 node equations. Only one mesh equation has V0 but it doesnt seem possible to introduce it into the rest.
user832075's user avatar
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Why we are using coupling capacitor in AC amplifier? [closed]

Why we are using coupling capacitor in AC amplifier?
Akshai PS's user avatar
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Magnetic force acting on a current loop while next to a current carrying wire

With I1=20A and I2=30A, find the net magnetic force acting on the loop. I am not sure how to even approach this problem. I know that the magnetic field of the wire is $\frac{\mu_0I}{2\pi r}$ and that ...
Z -'s user avatar
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If we change the direction of the connections in a step-down transformer, will it become a step-up transformer?

If we change the direction of the connections in a step-down transformer, will it become a step-up transformer?
Akshat Parmar's user avatar
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Why my DC thick charging cable is slower than a thinner one? (having same power rating & adaptor)

Does that means thick wire cause more current loss than thinner one?
Aarav Raj's user avatar
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How are quantum gates encoded in voltage/current waves for superconducting qubits?

From what I understand, the voltage and current waves propagate down the input transmission line, hit the nonlinear oscillator, and then bounce back toward the generator. How are gates such as the X ...
David L's user avatar
22 votes
12 answers
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How do computers store sound waves just by sampling the amplitude of a wave and not the frequency?

All of this just doesn’t make sense though. I mean, doesn’t the amplitude represent the loudness and the frequency the pitch? Aren’t they completely independent from each other? Is the book just ...
RedP's user avatar
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Power dissipated in transmission cable

Taken from NSAA/ENGAA 2022 (University of Cambridge's admissions assessments for Natural Sciences/Engineering) Electrical energy is transmitted at high voltage to a remote farm using an overhead ...
Daniel Williams Ruiz's user avatar
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Resistors in high frequency

My question is this: Can we use ordinary resistors like those we use in labs(1.2K ohm), in high frequency (like 4GHz)?
Hamidreza Moosavie Arsenal's user avatar
3 votes
3 answers
315 views

How are photodiodes fundamentally calibrated?

I have a theoretical question regarding the irradiance measurement of light sources. From the basics I know the following: Irradiance has the unit $\frac{w}{m^2}$, in the context of light that means: ...
iwab's user avatar
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Working of transistor

For the operation of the transistor, the base-emitter junction is forward-biased and the Base collector junction is reversed-biased. Due to the concentration gradient, electrons from the N side (...
Akshat Shrivastava's user avatar
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Why Faraday homopolar generator need brushes?

It is said that if one would attach a load physically to the rotating disc from center to rim no current would flow because both in the load wires and the disc itself currents would be generated in ...
Jarosław HboRodo's user avatar
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What is "capacitive effect" in terms of battery research?

For example, the paper I am reading states that the current was "periodically interrupted without changing polarity" to "demonstrate that the peaking behavior is not due to a capacitive ...
Alexis_Rose's user avatar
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Help understanding why built in voltage in PN junction created?

I was reviewing basic semiconductor physics and need some help understanding where my logic is incorrect. For a basic PN junction, the process of forming the depletion region is described as follows: ...
fordanjen's user avatar
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Doubt on time invariant system

Now I am delaying the output of a system (which takes $x \left( t \right)$ as input and gives $t \cdot x \left( t \right)$ as output) by $T$ then final output is: Let's denote the output of the ...
Qwe Boss's user avatar
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Why there is no EMF induced in this circuit

Why there is no current flow in this circuit? On this diagram, the copper wires are long and extend far beyond the magnetic field range and they rotate with multimeter or BT transmitter, magnet is ...
Jarosław HboRodo's user avatar
-1 votes
2 answers
72 views

From the physics standpoint, how should I align a USB Internet stick relative to the nearest cell tower in order to have the best signal? [closed]

I use this USB Internet stick: (Huawei E3372h-153) To connect to the Internet, I simply insert a SIM card into this stick and then insert the stick into a USB port of my laptop. Based on my ...
Mitsuko's user avatar
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Load Lines and Characteristic Curves

While studying electronic circuits involving diodes, I came across the concept of characteristic curve, which relates the voltage drop in a diode with the current through it. However, I was also ...
V Govind's user avatar
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Why do we still consider a doping concentration in undoped MOSFET devices?

I am studying cryogenic behaviour of MOSFET devices especially the evolution of threshold voltage with temperature. I mostly measure FinFET and FDSOI devices, all which have supposedly undoped channel....
Heomond's user avatar
2 votes
2 answers
92 views

How to collapse telescope image cone into an optical fiber?

I have an application where a telescope will be receiving light from a laser source. I would like to couple the output of the telescope, which is the image cone, into an optical fiber. Does anyone ...
Anthony Knighton's user avatar
2 votes
2 answers
77 views

Does KVL don't hold in pn junction reverse bias?

Does KVL hold in pn junction reverse bias because any reference about semiconductor physics provide that figure if we apply KVL around the loop won't be zero it will be equal to $V_{bi}$ then how KVL ...
amin's user avatar
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Does the built-in potential inside a diode change by making bias?

under thermal equilibrium the pn junction have a built-in field let say it's $E_{1}$ , if we make a reverse bias the external battery provide a permanent field $E_{2}$ , so the total field inside the ...
amin's user avatar
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If a downed powerline contacts the metal chassis of my car, can I touch any metal parts of my car while sitting inside of it?

consider the following situation. I parked my car underneath some high-voltage lines – let’s say 380 kV-lines. Suddenly, one of the lines breaks in the middle due to a storm and one end of the (still ...
ilovemaths's user avatar
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1 answer
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Increase water pressure (e.g. for watering the garden) using the principle of a hydraulic press

Does anyone know a device that incorporates this principle? Process is as follows: You get a lot of water at low to mid pressure (let's say 1 bar) A device D converts the work that 1 liter of water ...
zonksoft's user avatar
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1 answer
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1 Dimensional Linear Induction Motor Model Derivation Assistance

I'm reading through "Theories of the Linear, Induction Motor and Compensated Linear Induction Motor" Yamamura (1973) and was wondering if anyone can explain: Which law this "rot. H&...
Paul's user avatar
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Relationship between power output and power developed of a DC machine [duplicate]

Can someone please explain to me the relationship between the power output and power developed of a DC machine? Thank you
Aaron Joshua A Sazon's user avatar
2 votes
2 answers
58 views

Physically, up to what size is it possible to miniaturize the process node of a silicon chip? [closed]

With current technology we have managed to manufacture silicon chips of up to 3 nm for the semiconductor industry. To what size is it physically possible to make smaller the process node for these ...
Etherealist's user avatar
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2 answers
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Can computers recieve data wirelessly without being powered? [closed]

I'm not sure if this question totally fits here, but I think this is the best SE for it. Traditionally, to connect to the internet (a server), a computer must be on: powered and running. This means ...
Andrew Baker's user avatar
1 vote
0 answers
61 views

How do you calculate the force between an electromagnet and a piece of iron? [closed]

I am building a simple electromagnet, with an Iron core, and want to calculate the force it can exert on another piece of Iron when in direct contact with it (Basically how much weight it can lift). ...
Mahan Lamee's user avatar
1 vote
1 answer
128 views

Applying the equipartition theorem to charge on multiple capacitors

I asked this question here on the Electronics stack exchange, but it may be better suited here since the core of the question is about the application of the equipartition theorem to the charges and ...
Halleff's user avatar
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16 votes
9 answers
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Why does an MRI machine or other EMP generating machine not damage humans, but it will fry computers?

A sufficiently strong electromagnetic pulse can/will destroy smartphones and computers. I know somebody who went into MRI machine and forgot a Visa credit card in his pocket. The card was toast and he ...
ShoulO's user avatar
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1 vote
2 answers
102 views

Speed of electrons in a perfectly conducting wire [duplicate]

So we know that EMF of the battery provides an electric field in the circuit and thus accelerating the electrons inside them, so my question is that lets say if there is a perfectly conducting wire, ...
D J Sims's user avatar
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Adding more pair of Poles Vs Adding more armature condutor/winding - DC Generator

First of all, is it possible to have a DC generator with 4 poles and a single armature winding? If so what is the difference in DC output generated between a DC generator that has four poles and ...
Abhishek P G's user avatar
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1 answer
107 views

What is the highest frequency of alternating current?

What is the highest frequency of AC that we can possibly produce? is there only one method of inducing AC? for dipole antennas that can produce frequencies up to GHz, it must need an AC current, or is ...
Simon Lin's user avatar
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Is the turns ratio still equal to voltage ratio in a non-ideal transformer?

For a non-ideal transformer, is the following equation still true? $$ \frac{V_S}{V_P} = \frac{N_S}{N_P} $$ All the books I have consulted (mainly first-year undergraduate physics textbooks) merely ...
Tham's user avatar
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1 answer
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Current flow with no resistance

Imagine a simple circuit consisting of a battery with potential $V$ connected to a resistor with resistance $R$ by a loop of copper wire with $0$ resistance. It is obvious that a current $I=\frac VR$ ...
slithy_tove's user avatar
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Electric arc mechanism [closed]

The prominent justification for ground fault interrupter technology is inability of circuit breaker to trip if intermittent low level arcing is generated as a result of the ground fault, so would you ...
DYNAMICS's user avatar

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