Electronics is the study of electric circuits and electrical components, and the design of useful devices. Some questions in this tag may be more appropriate for the [Electrical Engineering(http://electronics.stackexchange.com/) SE site.

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14
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4answers
1k views

What's the physical meaning of the imaginary component of impedance?

As you know, impedance is defined as a complex number. Ideal capacitors: $$ \frac {1} {j \omega C} \hspace{0.5 pc} \mathrm{or} \hspace{0.5 pc} \frac {1} {sC} $$ Ideal inductors: $$ j \omega L ...
9
votes
1answer
398 views

Why do you only hear high frequencies when a microphone is near its speaker?

The phenomenon I'm talking about is positive feedback, as known from control engineering: when the microphone is too close to its speaker, it can "hear itself", so the signal will be infinitely ...
7
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2answers
2k views

Is it viable or possible to make your own transistor?

Just wondering if it is possible/viable to construct your own transistor, not small like todays, but the same scale as the one created at Bell Labs.
6
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3answers
11k views

Why can electricity flow only in one direction through a diode?

A few days ago I was soldering a small thing which contained a diode, a battery and some other useless things. Unfortunately, I soldered the diode reversed and it didn't work. When I reversed it ...
6
votes
1answer
629 views

How do Zener diodes survive the breakdown during reverse bias?

My highschool textbook states that Zener diodes are a special type of diode which is made of highly doped p and n junctions, and which can survive reverse bias - unlike normal diodes, which get ...
6
votes
1answer
685 views

How do Zener diodes maintain the potential across their terminals?

My physics book has a topic about Zener diodes being used as voltage regulators in the reverse bias. Well, I'm curious to know how does a Zener diode maintain the potential across its terminals after ...
5
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2answers
129 views

Layered CMOS structure question

I am trying to understand the workings of a CMOS image sensor. I understand that increasing wavelength results in an increased penetration depth in the silicon often used in CMOS image sensors. What ...
4
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1answer
443 views

Can electrons move through vacuum?

I studied that electronics is the branch of physics which deals with the practical applications of moving electrons through vacuum, semi-conductors and gasses. Can electrons move through vacuum?
4
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5answers
8k views

What would be the effective resistance of the ladder of resistors having n steps

I'm a tutor. This is a high school level problem. In high school, every one have might have solved a problem of effective resistance of a ladder of resistors having infinite steps. Now the problem is ...
4
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3answers
691 views

What are the effects of cosmic rays on consumer electronics?

When electronics/computer companies design a new chip, processor/ memory card/ or a solar cell, do they study the effect of cosmic rays on such electronically sensitive materials? If not, why not?
4
votes
2answers
1k views

Pn junction voltage drop?

This image from wikipedia, explains that there occurs a potential drop across a pn semiconductor junction, and an electric field confined to the depletion region. I already know the reason for the ...
4
votes
1answer
4k views

Why does it spark when I push a plug in the electrical socket?

When I slowly push a plug into the electrical socket I can often see sparks. Can anybody explain why? Can this be possibly harmful for the devices I plug in?
4
votes
1answer
532 views

Turn-on delay time for Laser diode

Do you know any simple explanation on the reason why the turn-on delay time on a laser diode is reducing while we increase the bias current? Turn on delay,is the time that the laser needs from the ...
4
votes
2answers
647 views

lifetime of a PN junction in a diode

diodes are made of silicon, which have been enriched in phosphorus and boron to create the PN junction. Since the electrons are always going in the same direction, from N to P in the junction, I was ...
3
votes
4answers
6k views

How does power consumption vary with the processor frequency in a typical computer?

I am looking for an estimate on the relationship between the rate of increase of power usage as the frequency of the processor is increased. Any references to findings on this would be helpful.
3
votes
3answers
4k views

What is a virtual ground?

What is a virtual ground? I would like to know what it is.
3
votes
4answers
11k views

Working of a p-n junction diode when forward biased

If p-type semiconductor and n-type semiconductor of a diode are equally doped, and if the diode is forward biased, then holes will move toward the n-type semiconductor and electrons will move toward ...
3
votes
2answers
898 views

Does van Eck phreaking really work, or is it an urban myth?

Van Eck phreaking, the ability to reconstruct distally the text on a CRT or LCD screen using the leaking em from the target computer, was in the news about five to ten years ago. It is talked about as ...
3
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3answers
44 views

Real silicon atom structure?

Text books say that a pure silicon atom has four electrons in its outermost orbit. How do the scientists know it has four electrons?
3
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1answer
397 views

Explanation of the Graetz circuit

My knowledge of circuits is pretty rudimentary and I've never really understood circuits, so I'm having trouble with the concept of Graetz circuits: When you register the voltage on the resistor R ...
3
votes
2answers
89 views

Why do batteries become weaker

I was thinking about my phone (Sony Xperia Z2) and when I put it to charge and remove it, the phone says "Please remove the charger, to save battery life," which is very intuitive question for a ...
3
votes
0answers
299 views

Smallest minimum feature size possible for transistors printed by photolithography

I'm doing a project about Moore's Law, one of the subtopics I've come to is photolithography. The way I understand it is that the MOSFET transistors are currently printed on a silicon wafer by ...
3
votes
2answers
356 views

number of electrons my laptop uses in a second

in order to confirm whether I understand the relation ship between amps, columbs and electrons I decided to try out the following. my laptop adapter's label reads 3.34 amps. I assume that: amps are ...
2
votes
2answers
183 views

Mechanical work to required battery power

I have a very practical question where I've calculated the mechanical work needed by a simple mechanical system by solving the line integral $W = \int_C \ F \ dx$. However, since I have a black spot ...
2
votes
2answers
389 views

Why do circuits work so fast?

Drift velocity (explained to me as how fast the electrons are moving) is really slow. My book says the electrons move at around 10 mm/ s. If electrons move so slowly how do circuits work so fast? If ...
2
votes
2answers
129 views

Is it possible to record the 'blue air" effect when a core goes critical?

I've been studying about radiation, and I saw something called the Demon Core. Apparently, it was a core that was under experimentation by the government in Los Alamos to see the exact point at which ...
2
votes
1answer
17 views

Why Microchannel Plates can be operated only in vacuum?

Why it is said that the Microchannel Plates can be operated in vacuum? What is the maximum pressure in which it can be operated? Also, while it is not operating, should it be kept in vacuum? Is this ...
2
votes
2answers
262 views

Problems in the modern semiconductor/electronics technology?

From what I have read, the problem with modern semiconductors/electronics seems to be quantum tunnelling and heat. The root of these problems is the size of the devices. The electrons are leaking out, ...
2
votes
2answers
753 views

What is the difference of the two stable states of a Flip-flop?

In electronics, a flip-flop or latch is a circuit that has two stable states and can be used to store state information. [...] Flip-flops and latches are used as data storage elements. Such data ...
2
votes
1answer
89 views

Why the electric potential of earth is zero?

For a localized charge distribution the potential is set to zero far away from the charge distribution (at infinity) Now, when grounding a conductor, i.e. connecting it to Earth, it is said that we ...
2
votes
1answer
26 views

What do I get when measuring on top of metal/insulator/metal by kelvin probe?

I am using a macroscopic Kelvin Probe for work function measurement. There's one confusing condition. If I measure a trilayer thin film stack with a structure of ITO(bottom)/PMMA(100-200nm)/Al(top), ...
2
votes
2answers
1k views

Why are there two quasi Fermi levels and only one Equilibrium Fermi level?

I am reading a book and I'm trying to understand the concept of quasi Fermi levels. For example, A steady state of Electron Hole pairs are created at the rate of $10^{13}\ \mathrm{cm}^{-3}$ per ...
2
votes
1answer
81 views

How does rust behave as a PN junction?

Reading about old-fangled radios the reference quoted below indicates it was/is possible to use a rusted razor (or perhaps any similar thin corroded metal strip) as a detector. Some resourceful GIs ...
2
votes
0answers
568 views

How did the Bardeen-Brattain point-contact transistor work?

How did the Bardeen-Brattain point-contact transistor work? What are the conditions under which a Schottky barrier injects minority carriers? In a bipolar junction transistor the forward-biased ...
1
vote
1answer
56 views

How big was the first transistor?

The first working point-contact transistor made in 1947 by Bell Labs. I'm looking for specific dimensions, all I've been able to find is "Fits in the palm of your hand".
1
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1answer
96 views

Why is spectral sensivity of a photodiode expressed in A/W

Can someone explain me the meaning of the A/W unit of the photosensivity when reading a spectral response function of the wavelength characteristic of a photodiode?
1
vote
3answers
94 views

Is it possible to produce gamma radiaton using radio emitter?

As in the title, I'm wondering is it possible. I think it is possible, because we have powerful enough radiotechniques and gamma radiation are just EM waves, not particles. However I think is ...
1
vote
2answers
133 views

Electrical analogy for stress and strain

It feels like the relation between stress and strain (and other mechanical properties) is analogous to that of some electrical properties (voltage and current?). I'm comfortable with electrical ...
1
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2answers
250 views

Explanation of NMOS processes

Gate (poly-Si + $SiO_2$) and $p^{-}$ silicon operate as capacitors. But how are voltages and charges applied? In order for inversion to occur, there should be charges formed in poly-Si, right? How ...
1
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3answers
640 views

Would connecting p-type and n-type semiconductors work as a diode?

If we placed p-type and n-type semiconductors close enough to be touching (see fig. 1), would this arrangement work as a diode? ...
1
vote
4answers
1k views

When does Thevenin's theorem not apply (modelling a power source with a ohmic internal resistance)

Most physics text books say that a power source can be modelled as an EMF with a internal resistance. This is also know as Thevenin's theorem or Norton's theorem. However I have read in some sources ...
1
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1answer
41 views

Calculate TEC efficiency

I am currently doing a small experiment using a Peltier to cool 250ml of water. My aim is to achieve the cooling of 250ml from 23degC to 8degC in under 20minuets which I have done by strapping the ...
1
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1answer
61 views

What is the speed of electrons in a transistor?

What is the average speed of an electron in a MOSFET transistor, and how can you calculate this? I've heard people throw terms such as "drift velocity" and "Fermi velocity" around, but I've never ...
1
vote
2answers
57 views

Can you replace the backlight of a thin film transistor (TFT) with a mirror?

I basically know how TFT' displays work. They have on both sides a polarizing foil, in 90 degrees with the crystals in the middle modifying which light particles should pass through or not. The light ...
1
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1answer
49 views

Diodes (Forward biased)

Why does the width of the depletion region decrease,when the diode is forward biased?Is it because the ions have moved to p-junction,or n-junction? Please clarify.
1
vote
1answer
235 views

How to understand exciton?

I know that exciton is an electron and hole orbiting around each other(at least that is what I have heard). So if the hole is a hypothetical particle with a plus sign, mining that it is a lack of an ...
1
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1answer
339 views

Electrical conductivity of an intrinsic semiconductor

On which factor does the electrical conductivity of an intrinsic semiconductor depend? It doesn't have an excess of charge carriers in fact, does it?
1
vote
3answers
206 views

Electronic filter

Can you explain, please, step-by-step how an electronic filter does work? For example, high pass filter. I know It's a trivial things, but I can't get it completely. Don't bring me formula and etc. ...
1
vote
2answers
584 views

In the diode equation, why the exponential $\exp$ and the ideality factor $n$ are there? What do they represent & what is their significance?

In the Shockley diode equation, why the exponential $\exp$ and the ideality factor $n$ are there? What do they represent & what is their significance? I have to work on Solar Photovoltaics, and ...
1
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2answers
276 views

Nodal Analysis of an electrical circuit

I have several doubts about solving circuits. Can any circuit be solved using Nodal Analysis? If some circuit can be solved using Nodal Analysis, can it be solved using Mesh Analysis too? Why do we ...