Questions tagged [electrical-engineering]

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5
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3answers
106 views

What is the name of the shape of the iron core in a transformer?

I'm researching on transformers and curious to know about what this shape is called (the actual core block, ignore the wires around it).
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0answers
7 views

Do dielectrics feel significant magnetic force?

If we apply an high frequency ac magnetic field to a very dielectric material (order of millions) with very high refractive index (order of thousands) does it experiences any significant forces?
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1answer
26 views

AC field propulsion

Assuming that we have a metamaterial that can slow down the velocity of propagation of changes in an EM field to around 15 000 m/s (without felling or applying any forces), can we build a propulsion ...
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2answers
49 views

Is the performance of electronic devices affected by their age? [closed]

I always wondered what happens inside an electronic component during its lifetime. I am aware that passive or active electronic devices can have their performance decreased over a long period of ...
0
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1answer
21 views

Highest refractive index dielectric

What is the material or metamaterial that is a very good dielectric and has a very high refractive index at least in frequencies below $500\ MHz$?
3
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0answers
31 views

Attenuation in microwave and optical communications

I have read that the attenuations of microwave transmission lines and optical fibers are ~1 db/m and ~ 0.2 db/km, respectively. I understand that these values depend on the geometry, design, and ...
0
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1answer
24 views

Do electrons on $n$-side loses its energy to fall into holes on $p$-side during forward bias in a diode?

So in a diode in forward biased condition the electron from n side recombines with the hole in p side.I also understood that the electrons in n type are in conduction band and holes in p type are in ...
5
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2answers
1k views

What's the purpose of capacitors in parallel

In my school textbook it is written that the capacitor acts as a filter, that is, it decreases the fluctuations in the potential difference across the load. But since all the components are ...
0
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3answers
57 views

Why does the power remain constant during the stepping up and stepping down of current in transformers?

I understand quite a bit of transformers, their structure and other concepts and formulas related to mutual induction. However I'm not able to explain why the electrical power has to be constant ...
-1
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0answers
7 views

The correct formula for the frequency of a kacher brovin circuit? [migrated]

I was planning on building an kacher brovin circuit Now, I know for a regular tank circuit Frequency f=1/(2pi(sqrt(L1C1))). However I read that the frequency of a slayer exciter is using L2 and its ...
0
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1answer
22 views

With a half-wave rectifier, wouldn't the charges accumulated on one side?

In a normal alternating current circuit, the charges just travel back and forth, so they won't accumulate. However, if only half wave can pass through, then will the charges get accumulated on one end ...
0
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0answers
28 views

Does writing a file to a solid state drive change the mass? [duplicate]

Some stupid meme my sister showed me went along the lines of "will my laptop get heavier if I put more files in it?", but it was sufficient to get me thinking--is there an energy change &...
2
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1answer
24 views

in photoelectric effect, where do electrons go when they are ejected from metal?

When light shines on a metal, electrons are ejected from the surface of the metal provided the energy of the photons are greater than the work function of the metal. My question is, (1) where do the ...
1
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3answers
209 views

RC circuit discharge while being connected to a battery?

I am facing a conceptual problem in analyzing the following situation which was part of a physics exam: A series RC circuit with $R = 200k \Omega$ and $C = 10 \mu F$ is connected to a 5V battery and ...
-1
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0answers
18 views

Getting 12v, 110mA supply [migrated]

I am not too familiar in electronics but I am currently using them for a Computer Science project. I am connecting an electromagnetic door lock to a SPDT relay so that the door can stay on NC and then ...
0
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0answers
9 views

Reducing current of a driver cell in a potentiometer

In a potentiometer in order to reduce the current from the driver cell shoudn't the resistor be connected in front of the positive terminal rather than behind it?
1
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0answers
23 views

In an AC Current, if the voltage is high, does this “amplify” the radiowave emissions without changing the frequency?

Hello My question comes from my interest in antennas i suppose: I understand that antennas utilize alternating current to generate EMF Waves along a particular frequency depending on how quickly the ...
0
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1answer
26 views

How much energy do I need to charge an electric car? [closed]

Suppose I have an electric car with a battery capacity of N kWh, how many kWh of power do I need to recharge it? It can't be a precise match of N - some must be lost through heat, powering the ...
-2
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1answer
23 views

In which household equipment can i find an alternator or a generator or a dynamo (about 17V)? [closed]

equipment required: dynamo or an alternator or generator (all should be small about 17V). As due to COVID19 i am unable to buy any of the mentioned equipment as the online shopping service providers ...
1
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1answer
38 views

Heaters in parallel and series [closed]

I have a heater rated at 13 kW with two identical heating elements connected in parallel with a 240VAC power supply. If I connect elements in series instead what should be my expectation: That the ...
0
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0answers
19 views

A problem with high pass filter circuit

What physically happens when the input frequency is "too high"? At "normal" frequencies the circuit should act as expected and block lower frequencies while getting only higher ones. I found that if ...
0
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1answer
380 views

How to calculate total power generated?

I have a circuit with a piezoelectric transducer which converts mechanical energy to electrical. The ceramic is connected to a 1 Megaohm resistor and a voltmeter which reads voltage. If I want to ...
1
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2answers
14 views

AC current waveform

Is there any reason one would choose a sine wave instead of a rectangular wave for example? What are the differences between them? Why would one prefer one waveform over the other in certain ...
0
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1answer
560 views

Quantum tunneling in zener diodes

Well Zener diodes operate as a voltage regulator because of the Zener effect-Quantum tunneling . Quantum tunneling is the effect when an electron faces an energy barrier but after the energy barrier ...
1
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1answer
64 views

I can't seem to comprehend electrical circuits [closed]

I don't seem to fully get the mechanism going on. A potential difference is applied, then an electric field pushes electrons from low potential to high potential. Now, a few questions: If electric ...
5
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3answers
5k views

What exactly is a phasor?

What exactly is a phasor? I was reading about alternating current when I came across the following definition: A phasor is a vector which rotates about the origin with an angular speed(suppose $\...
1
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2answers
61 views

Can 'distance' be mathematically described as the convolution of velocity and time, in time domain?

I have phrased the question as such, to confirm that convolution of the two functions raises the dimensionality of the convolution product. So, if I do convolution of velocity and time, then the ...
0
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1answer
31 views

Magnetic analogy to the transistor?

Is it physically possible to substantially change a large magnetic field with a smaller one analogous to the electric field at the gate being able to partially or completely block the flow from source ...
0
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0answers
18 views

BJT phototransistor operation

I was wondering if I have understood the working principle of the BJT phototransistor. When light is absorbed by electrons in the emitter, enough electrons are energetic enough to cross the depletion ...
3
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1answer
70 views

Does this setup defy conservation of energy?

Suppose we have two wire loops of the same dimensions placed adjacent to each other. The first loop is connected to an AC source, the medium inside the first loop is air and the medium inside the ...
1
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1answer
60 views

How Equilibrium is Reached and Voltage Shared in a Series Circuit with Two Resistors [closed]

I've been reading up on basic electronics recently and to help me understand things better, I've been writing down my understanding of what I've read in layman's terms. One thing I've struggled with ...
2
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2answers
942 views

What are the wavelengths of the red, green, and blue lights used for making LED pixels?

LED screens in televisions and smartphones use pixels that use a combination of Red, Green, and Blue diodes that can produce any color when used in the correct proportion of intensity. My question is,...
1
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2answers
46 views

Wireless data transmission more than a bit at a time

I'm not that educated in wireless data transmission, but, the basics of frequency modulation and or amplitude modulation are quite basic. Is there any examples of transferring more than a bit at a ...
1
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1answer
5k views

Shockley's diode equation

We owe a debt to Bell Labs with Shockley, Bardeen and Brattain for inventing the semiconductor. All have now passed on. I remember seeing my first transistor radio in the early 60's. Shockley ...
0
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2answers
48 views

How does electron hole recombination cause a base current in a transistor?

Can anyone help me in understanding the idea behind the recombination current? If a recombination takes place, then how does it lead to a current as in the base-emitter junction of a transistor?
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0answers
23 views

Electrical engineering question to reach a given form using the maxwell equations in circular cylindrical coordinates

My aim is to transform the term in $$(e^{-im\phi}\Delta_\perp E_\phi+\nabla_\perp(e^{-im\phi})\cdot \nabla_\perp E_\phi)$$ using Maxwell equations in circular cylindrical coordinates to the simplified ...
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1answer
224 views

Patch antenna excitation

How can we excite the patch antenna in different modes like TM10 and TM30? If a microstrip patch antenna resonates at TM10 mode can it resonate in other modes also like TM30?
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0answers
15 views

Which part of the magnetizing current is responsible for the leakage flux in a transformer?

This is the phasor diagram of the two winding transformer. Shouldn't there be another component of the magnetizing current(Im) along itself ( but of lesser magnitude than Im) ,which is responsible ...
1
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1answer
177 views

Why is the emitter current of a common emitter slightly greater than the collector current?

I'm trying understand where electricians came to agreement that Ie = Ib + Ic. I know that the base of a NPN transistor is very thin, allowing electrons to flow through to the collector which explains ...
1
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0answers
36 views

Explanation of behaviour in calculation of mutual inductance between two circular coils [closed]

I am working on calculation the mutual inductance between to coils in a project concerning power transfer. At the moment I am working on analyzing the mutual inductance between two coils but I am ...
3
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1answer
50 views

Phase Difference in mutual coupling

I was reading about oscillator circuit then in my textbook it was written that we get phase change of π at mutual coupling.But, when I workout through mathematics of situation (which I have shown ...
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0answers
36 views

Can we use the photochromic lens as a MOSFET?

So the way a MOSFET works is it has a channel through which either hole or electron current is controlled through the gate voltage making it a switch. Now a photochromic lens has changeable ...
1
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1answer
1k views

Resistance of Light Dependent Resistor (LDR)

Is there a mathematical expression relating the resistance of Light Dependent Resistor (LDR) with light intensity?
1
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1answer
154 views

Is a radio receiver antenna a capacitor?

I think so, but its capacitance should be very small, so how can the antenna correctly receive the signal, the low capacitance wont bother the signal?
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2answers
62 views

Why does material change electrical property based on frequency of input electrical signal?

I was investigating whether dry soil would conduct electricity. What I found was that at 60 Hz frequency (i.e. power line fell to the ground), dry soil is a very good conductor. But if you increase ...
0
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1answer
418 views

About The foxhole radio: coil rotation times, whether capacitor's needed

I recently tried to make a DIY foxhole radio. Althogh I made it according to the manual (140times coil rotated, ground(220V), blued razor blade, pencil core and antenna (just a steel stick about 1 ...
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0answers
27 views

electrical susceptibility and magnetic susceptibility

Is there a difference between electrical susceptibility and magnetic susceptibility or they are the same thing? if they are different what are the basic definitions for these terms (no mathematics ...
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0answers
56 views
4
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2answers
24k views

How does current flow from the emitter, through the base and to the collector in a NPN transistor?

So, I understand that for a NPN transistor to work the emitter-base junction needs to be forward biased and the collector-base junction needs to be reverse biased. I understand how current flows from ...
0
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0answers
19 views

Induction cooker

I was using an induction cooker and I kept my steel utensil empty on it and switched it on. After some time the bottom part of it became red hot but the upper part of it was completely cool. Why does ...

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