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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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, ...
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1answer
38 views

Unknown pulses from SiPM without any source or detector?

I have a SiPM set up with its PCB, no amplification at all, reading out to an oscilloscope. If I supply 29.8 V, which is the maximum power (with overvoltage), I get some random peaks on the ...
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1answer
1k views

Why do lower frequency need more cone excursion?

I am not 100% sure about this,but my current understand of loudspeaker is that moving coil woofer with certain fixed value surface area playing 1000 Hz frequency at 100 dB spl will be moving back and ...
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1answer
73 views

What is the difference between Si pixel and Si strips used in CMS Inner tracker at CERN?

What is the difference between Si pixel and Si strips used in CMS at CERN? Both are used for tracking and as the CERN website mentions, they are also based on the same working principles. Or are they ...
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1answer
320 views

Memristors: how are memristors modeled in terms of impedance?

How are memristors modeled in terms of impedance? I have been searching the net for memristors, but could not get much of an idea. I'm not interested in how memristors are made (by combining ...
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1answer
118 views

Accumulation Region of an NMOS

I'm trying to get a better understanding of how the NMOS works when a negative voltage is applied to the gate. So I currently understand that the $P^-$ substrate is lightly doped with such a ...
2
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1answer
49 views

Won't the Power be dissipated in the first quadrant of this graph?

In the following picture: In the first quadrant of the V-I graph(for an Independent Current Source, where the voltage supplied is positive on the top) won't the power be dissipated instead of being ...
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1answer
3k views

The width of the space charge region in a pn-junction

Given a pn-junction as in the picture below. Which quantity determines the width of the space charge region? Or in other words, why don't the electrons in the n-doped region wander towards the ...
2
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1answer
628 views

Why does small change in Base current causes a larger change in collector current in case of transistors? [closed]

Why does small change in the base current causes larger change in the collector current. That is say if I increase the base current buy a small amount why the collector current increases by a very ...
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1answer
56 views

Effect of charge on electric circuit in free space

Assume I put some electronic device, a laptop for example, in free space. Now add electrons to the object. It will become progressively more negatively charged. At what point will the laptop (or ...
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1answer
179 views

Why, microscopically, is the voltage drop across a resistor affected by the current through it?

If voltage is a potential difference, describing how much energy will be lost per unit charge as charge carriers pass through the resistor, why would the rate at which charge flows (i.e. current, $=dq/...
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2answers
319 views

Shining light (of a particular frequency) on an insulator to make it into a conductor

Recently I read about band theory of solids. The energy difference between valence band and conduction band determines the conductive property of solids. Suppose I take an insulator and shine it with ...
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2answers
93 views

Why are holes (in a semi conductor) regarded as particle?

Can I say that holes in a semiconductors are treated as current-carrying conventional direction ?
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1answer
4k views

Calculating Boltzmann constant using semiconductor

My task from the latest laboratory exercise in physics is to calculate Boltzmann constant from known temperature, current and voltage. We were given this circuit: By changing the resistor value, I ...
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2answers
251 views

What will be the effect of placing a light source very close to a photodiode?

What will be the effect of placing a photodiode really close to a laser source and what should be the appropriate distance between a light source and photodiode to get maximum output current?
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1answer
2k 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 ...
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1answer
252 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), ...
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1answer
3k 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, meaning that it is a lack of an ...
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1answer
240 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 ...
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2answers
2k 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 ...
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0answers
11 views

Why does this magnetic charger cause short circuit when it sticks to the metal leg of my table? [closed]

Recently, I have bought this product. It is basically a USB cable, with a magnetic end, and a tiny attachment that goes into the mobile device. I plugged it into my laptop cooling stand (which has ...
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0answers
49 views

Distance $E_F-E_i$ in a compensated semiconductor

Given two energy level diagrams for a compensated conductor: At $0~\text{K}$ At $500~\text{K}$ I want to determine for which diagram is the Fermi level closest/farthest from $E_i$. It's a ...
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31 views

What is phase sensitive detection?

The lock-in amplifier is said to have a phase sensitive detector which compares the phases of the reference and incoming signal and is thus able to recover a weak signal from an overwhelming ...
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0answers
104 views

Conductivity of a heavily doped semiconductor at Absolute zero temperature

As the Fermi level moves toward the conduction band in an n-type semiconductor; when heavily doped, it moves into the conduction band of the semi conductor. So, will the semi conductor behave as a ...
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2answers
128 views

What is the need of term 'closed circuit'? [closed]

If a circuit is a closed path in which charges can flow then why do we have the term closed circuit? Doesn't the definition mean that a circuit is always closed.
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0answers
97 views

Can seebeck chips be used to extract Peltier chip waste heat?

I understand that a problem with employing the Peltier effect for the purpose of cooling is that it produces a significant amount of heat on the hot plate. But why don't we use seebeck optimised chips ...
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0answers
50 views

How to control a dc motor? [closed]

I am in 8th standard and I am doing a project on 3d printing pens. I want to know how to control a dc motor, so that when I press a button it should increase its speed gradually till it reaches its ...
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0answers
29 views

Have the BaF2 scintillators a strong correlation with the input current that cause the shifting of the centroids in the distribution?

In gamma gamma correlation I suspect the presence of systematic error maybe caused by a non optimal voltage according to someone there is a quadratic correlation between centroids position in the ...
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0answers
399 views

Piezoelectric effects of naturally shaped quartz crystal for maximium Q?

Background Based on helpful comments and links here and also from my question on the electronics stackexchange, I have learned that the quartz crystals are nature's transducers of energy, allowing ...
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3answers
5k views

Why capacitor pass AC and block DC current? [duplicate]

We know that in circuit capacitor block the DC current and pass AC current. My question is how a capacitor block DC and pass AC?
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0answers
641 views

Concepts in Gabriel Kron's later papers

Gabriel Kron was an important research electrical engineer known for applying differential geometry and algebraic topology to the study of electrical system. Towards the end of his career he published ...
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3answers
2k views

If we connect a block of p-type semiconductor only to a positive terminal, will it become positively charged?

Connect the positive terminal of a battery to a piece of p-doped semiconductor, say, silicon doped with boron. Will the terminal pull electrons out of the doped silicon, or equivalently, inject holes ...
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1answer
2k views

Increase of threshold current by temperature in a laser diode

I read somewhere that if we increase the temperature of the material in a laser diode the threshold current for lasing also increases. Can someone explain to me why is this happening? What is the ...
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2answers
105 views

$1/f$ noise: is it limited?

Basically my question is: I have this doubt because in contrast to the limit $f \to \infty$ (which is an idealization because all system behaves as a low pass for enough $f$), we can perfectly build ...
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3answers
2k views

How does Ohm's law apply to superconductors?

As radio amateurs we've all learned the various relationships of power, voltage, current and resistance as expressed in Ohm's Law. My question relates to the following simple circuit showing an ideal ...
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3answers
144 views

Can we have electronics with charge carriers OTHER than electrons?

Ions perhaps? Or other elementary particles with charge?
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1answer
164 views

How can monitors display a sharp image, if light travels in all direction?

The question title might be a misnomer, help me improve it. My question is, from my understanding, a light travels in all direction from it's origin point. Also I assume that in the example of a ...
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3answers
69 views

Question about full wave bridge rectifier

Sorry if this is a stupid question, what I know is when a diode is forward biased, it conducts current, when it is reverse biased, it acts as an open branch if its $ PIV \geq V_{in}$ But in this ...
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3answers
3k views

Confusion on AC in LIVE & NEUTRAL WIRE

So if an AC current means the elctrons are alternating or changing direction in a given time, how does this apply to live & neutral wire, don't they flow in one direction only? Please answer it as ...
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2answers
105 views

Existence of conduction electrons in pure Si at room temperature

Silicon has a bandgap of ~1.1 eV whereas the room temperature thermal energy is ~0.04 eV. But we still find electrons in the conduction band for a pure silicon wafer, away from any radiation. I ...
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2answers
582 views

Does an electron physically flow? [duplicate]

In a DC current in a conductive wire, is it more accurate to think of one electron wiggling its way through a sea of electrons... or to think of one electron bumping into another, which bumps into ...
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2answers
348 views

Can we prove “Lumped element model” mathematically?

Maybe this question is both in the fields of engineering and physics. As it seems the electrical quantities like Resistance, Capacitance, Inductance, and so on are quantities we assign to distributed ...
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2answers
984 views

What causes reverse leakage current in an LED?

I've read it can be due to 'intrinsic semiconductor conduction' and surface conduction. The LED I am looking at is InAs, which is apparently prone to surface conduction. I have tried out what these ...
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2answers
2k views

Electronics book for physics undergraduates

I am going through very hard time studying electronics, I studied little electronics at high school (what is diode, transistor, etc). Now in clg now I need electronics to study, I don't understand ...
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4answers
1k views

Potential Difference Across Components in Parallel & Series Circuits

So I have two questions, but they're kind of linked so I'm putting them in one. 1) I have a simple circuit with a battery connected to three lamps in series. If I then add a second battery but ...
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2answers
129 views

Why is electricity so successful (how to explain the variety of transducers we have discovered)

From piezoelectric crystals, to loudspeakers, microphones, hydrophones, strain gauges; electricity possesses the amazing ability to transfer energy/information to and from so many different media. I ...
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1answer
759 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".
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2answers
23k 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 ...
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1answer
2k 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?
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1answer
65 views

How is quantum physics translated into the world of electronics? [closed]

I remember watching a documentary about early works in quantum physics and how it was essential to the microelectronics revolution and the invention of the transistor. What part exactly helped? Is ...