Questions tagged [electronics]

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(https://electronics.stackexchange.com/) SE site.

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Linear Energy Transfer & Absorbed Dose

I started to learn about radiation effects in semiconductor devices and integrated circuits. I am trying to understand the physics of it. Have some questions. The first is if you could suggest a good ...
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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 ...
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32 views

How does RF communication between electronic circuit elements affect the circuit?

The other day, a friend and I were looking at a simple resistor-capacitor-inductor circuit. As we were looking at the circuit, he mentioned that the capacitors and inductors "talked" to each ...
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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 ...
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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 ...
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1answer
30 views

How to reduce 5V to 3.7V and current 0.8A? [closed]

I have been working with arduino and I want to connect a motor which runs at 3.7V and 0.8A, but there is 5V output in arduino. So how do I fix this problem? Please help me with this.
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What is the flat band voltage?

I do not understand what the flat band is. I am studying the MOS structure and the teacher told us that the flat band voltage is the voltage that we have to apply to the MOS so that the effect of the ...
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What is the difference between DC base current and signal current in CE transistor amplifier? [migrated]

I came across a sentence that " if the DC base current has to be 10 times the signal current....".I could not understand, what is DC base current as I have just read about Input current and Output ...
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Why a semiconductor exhibiting negative differential resistance is inherently unstable?

A semiconductor exhibiting negative differential resistance is inherently unstable. Why is that? Why a random fluctuation of carrier density at any point in semiconductor produces a momentary space ...
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Can someone explain why electrons of n type(conduction band,higher energy),fall into holes in p type(valence band,lower energy) during forward bias?

As I was learning semiconductor physics I learned that holes are deficiency of electrons.I also learned that the electrons from the n type material combine with the holes in p type and the electrons ...
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Can you apply horizontal shift to obtain the absorption spectra for III-V ternary and quaternary compounds

For a multi-junction (MJ) solar cell application, can you apply a horizontal shift to obtain the absorption spectra when you don't have the available data? For example, if you know the absorption ...
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Intrinsic carrier concentration and bandgap

My understanding is that the intrinsic carrier concentration of a wide bandgap material tends to be lower than that of a narrow bandgap material. $$ n_i = \left(N_cN_v\right)^{1/2}e^{\left(\frac{-E_g}...
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Potentials in a MOSFET [migrated]

My knowledge is very basic. For this question I consider n-channel enhancement mode MOSFET. I see some MOSFETs have 3 terminals, while others have 4 terminals. This forth terminal is the base ...
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1answer
38 views

Rainbow Colors on a Water Droplet on a Screen

I accidentally fell a water droplet on my mobile phone's screen. But on observing closely I saw that the water droplets showed rainbow colors (the screen was mostly white). By rainbow colors I mean ...
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3answers
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If voltage causes current to flow how can a battery have constant voltage but supply different amounts of current?

The question arises from the fact the voltage provided across battery terminals is constant no matter how much current is drawn (for non-ideal batteries the current draw is limited but still can be ...
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47 views

Does the shifting of the Fermi energy level of an intrinsic semiconductor mean that $n \neq p$?

It has been stressed out in the books that I've consulted that, for an intrinsic semiconductor, $n=p$. However, with this in mind, they also derivate the following equation: $$E_{F_i}=\frac{E_c+E_v}{...
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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 ...
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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 ...
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2answers
45 views

By what mechanism does a solar flare overload electronics?

I apologize for my ignorance, but I lack the underlying knowledge to meaningfully research this myself. My knowledge of both Solar Flares and EMPs comes almost exclusively from pop-sci reading. I've ...
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1answer
52 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 ...
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Why is the sum of currents in a diode constant?

Why is the sum of currents in a diode constant? Please answer my question I'm very appreciated
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What is the strength of current in electrolytes?

if a battery is connected to an electrolytic cell, what is the magnitude of the current in the electrolyte compared to the the magnitude of the current in the wire? This doesn't make sense to me ...
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46 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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1answer
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What are good books and other resources to study the Cryogenics?

I'm beginner in cryogenics. Also please suggest something which will be useful for study of Electronics at Cryogenic Temperatures.
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Confusion regarding the quasi neutrality approximation for PN Junction analysis

Why are they called quasi neutral and not exactly neutral? What happens which make them that? In the analysis we have done to derive the I-V characteristics , we always maintained neutrality where ...
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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 ...
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How do you calculate the reflectivity of material from its conductivity?

How do you calculate the reflectivity of material from its conductivity? For example, gold at v=9x10^12/s (this problem is from the electronic property of material by Hummel). Is it possible to use '...
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1answer
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Is “quaternary” adjective redundant while speaking of InGaAsP?

I'm reading an article. One sentence looks as following: The 500 nm thick waveguide layer consists of an InGaAsP quaternary layer But since InGaAsP is quaternary compound, why do they write ...
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1answer
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p- and n- contact metal difference

I'm reading an article about some electronic components and the authors specify that they used p- and n- contact metals, but without giving details about those metals, or what material are they really....
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393 views

Why complex numbers are used in electronics? [duplicate]

The impedance of a capacitor or an inductor is imaginary. How do we know these quantities are imaginary?
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42 views

How can a doped piece of silicon (with different concentration) still be intrinsic? [closed]

I am trying to solve a question which says: A piece of silicon is doped with Nd = 1.8*10^(13) and Na= 3.8*10^(13) Prove it is intrinsic at 500k. I don't know how is it possible for silicon to be ...
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Does aluminum in between stop induction cooktop from warming iron?

There is an ongoing discussion about induction cooktops on Seasoned Advice. The situation in nutshell is: About 1 cm of aluminum on the cooktop. About 1 cm of iron on top of the aluminum. My ...
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1answer
60 views

Why a photon cannot change the crystal momentum of an electron?

We know that absorption of a photon excites an electron from the valence band to the conduction band without changing its crystal momentum $\vec{k}$. Why can't a photon change the crystal momentum of ...
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1answer
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Derivation on the effect of temperature on Fermi distribution function [closed]

With reference to Section 10.7 Effect of Temperature on Fermi Distribution Function from the text Solid State Physics, 2nd ed., M. A. Wahab, the last two equations are given like this: $E_{F_0}^{3/2} ...
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Physics behind impedance matching and reflection

I have been looking for cause of signal reflections in transmission lines everywhere it is concluded that the reason is impedance mismatch. I understand that if the impedance changes in the path of ...
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1answer
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RLC Bandpass Filter network

Can anybody tell me what the "s" in this equation is? I am looking for the transfer function of this circuit
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Can an extrinsic semiconductor have a positive temperature coefficient?

My professor says in his notes that, because electron mobility decreases when temperature increases high enough, the conductivity of an extrinsic semiconductor actually decreases at such temperatures. ...
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Emitter current doubt

In my semiconductor lesson about npn transistor I found emitter current (Ie)=base current(Ib)+collector current(Ic).Now for practical purpose we can get the values of different current using micro and ...
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1answer
24 views

Signal demodulation in a frequency mixer

Let's assume we have a signal $f(t)=A\sin(\omega t)+B\cos{\omega t}$. In order to isolate the '$A$-part', the signal is mixed with an oscillator signal $g(t)=\sin(\omega t)$ generating a constant ...
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1answer
79 views

How do semiconductor devices break when hot? [closed]

When a diode gets too hot it may start to conduct in both directions, and it may remain this way even after cooled down. What happens in this process? I found some answers that suggest melting. ...
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3answers
116 views

$V$-$I$ characteristic of a solar cell

please explain the VI characteristics of a solar cell. The characteristics is given in my book without any explanation. How can the Voltage decrease on increasing current shouldn't it be opposite. ...
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1answer
69 views

Passive dissipator block between two peltier cells seemingly raising overall temperature differential

I am experimenting with stacked Peltier cells trying to build a simple diffusion cloud chamber. I noticed that when simply stacking two peltier cells the upper side reaches a temperature (around -15 C)...
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59 views

Why don't cell phones pick up music in phone calls? [duplicate]

Why is it that a listener on a cell phone cannot hear music on the other end? For example, the source phone is located either in a car with music being played, or is at a concert. The listener hears ...
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1answer
333 views

Noise cancelling speakers to cancel sound in the room [duplicate]

A thought of mine from class, where not everyone is the "silent kid" type. The teacher would very often need to shout to keep the class barely quiet enough for the students who actually are paying ...
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What happens to an insulating barrier in a semiconductor nanowire during thermal fluctuations?

I was wondering about semiconductor nanowires with a barrier during thermal fluctuations. Could anybody explain or account for why (or refer me to an article that does), when running a current ...
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1answer
123 views

Drift velocity component of electrons in alternating current

I'm not sure if this question will qualify as cross-posting, but feel free to tell me if it does so that I can delete it. However, this question certainly does relate to both physics and electronics, ...
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2answers
81 views

Is the EMP threat to the power grid supported by physics? [closed]

Every once in a while I come across some article saying that our modern power grid could be knocked out of commission for up to a year by an electromagnetic pulse. I'm skeptical of such warnings. ...
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77 views

Why mobile phone and laptop computers’ screens are polarized?

Why is it necessary to use either a linear or a circular polariser for mobile phone and laptop computers’ screen?
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23 views

Is there any factors depends for electromagnetic waves?

I am staying in hostel. One person said me that he is getting better connection with the wifi when the door is opened. I am wondering that what an electromagnetic wave can do with the door? Is there ...
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MOSFET Mobility

The surface mobility is lower than the bulk mobility because of surface roughness scattering What is surface roughness scattering? How does it affect the mobility?

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