# Tagged Questions

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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### Generator phase noise influence on its averaged signal

I need to estimate averaged signal of a generator with known phase noise and the amplitude noise can be neglected. The averaged signal of the generator is expressed as:  \langle A\exp{i(\Omega t + \...
150 views

### Spin FET Transistor

Spin FET Transistor. When a gate voltage is applied to a current of spin polarized electrons, a spin precession will occur. If this spin precession is enough to make the bulk electron spin ...
196 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 ...
445 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 ...
2k 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 ...
1k 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?
456 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. ...
1k 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 ...
247 views

### Could a variable capacitor divider replace a Variac?

Hmmm... You can definitely drop down the voltage, and ideal capacitors don't dissipate any power. So it seems, at first glance, that you could use a capacitor divider as a lossless voltage step-down ...
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### Capacitors in space [closed]

I'm new here and I have a question for all of you. What happens to a capacitor in open space? There are different kind of them, which one of these is better to use there? And... We know that if we ...
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### what is the effect of temperature on the resistance of a photoconductor?

As we know, for a photo conductor resistance tends to decrease with increase in irradiance, but with greater irradiance comes greater temperature. Also we know, photo conductors are semiconductors,...
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### Cds photoresistor cells [closed]

We understand (from Wiki) that when light hits the photoresistor cell, the resistance goes down, electricity flows more easily. But dont understand how resistance going down would work to turn OFF a ...
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### Electron jump into a transistor to read qubit state

Prof. Andrea Morello, a quantum physicist, in one of its quantum computer models uses the spin of the outermost electron in a phosphorus atom to represent a qubit. This atom is embedded to a transitor....
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### Thermistor is more sensitive than metals [closed]

Can anybody tell me, why a thermistor is much more sensitive at temperature variation than a metal?
26 views

### Which law of physics is applicable for communication? [closed]

What is the physics behind communication like internet, mobile phones etc. What are the equations?
15 views

### Electron gun and oscilloscope

Aren't the electrons exhausted in the electron source of electron gun? And what is the fate of electrons that strike the sulphide coated screen to produce luminescence?
25 views

### Why does the metal mesh in an electric swatter make a whirring sound?

I have an electric bug swatter that operates on a rechargeable lead acid battery. I had one before that operated on disposable batteries and when it was turned on, it made a high pitched whining noise....
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### Is it possible to make a capacitor of required specifications using aluminium foil? [closed]

I wanted to make a FM radio transmitter but I was not able to get a capacitor with the exact rating of certain micro farad and pF. But I live in a poor country and I can not find them in the local ...
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### How do electrons move across depletion region in npn transistor? [duplicate]

Concerning the base-collector barrier, the electrons coming from the emitter move through the barrier using diffusion mainly and drift. Does carrier injection happen as a result of these two ...
30 views

### How to produce sine wave heat generator?

I have taken a lab course this semester and in the experiment of finding thermal diffusivity of brass they are using square wave heat generator(by a simple circuit which gets on and off at regular ...
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### Calculation of RMS current in half wave rectifier

While calculating RMS current in half wave rectifier, why we will consider only half wave that means only we consider the limits 0 to pi. But here RMS current is for AC input..so why don't we consider ...
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### 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/...
143 views

### Numerical Solution of 1D Boltzmann Transport Equation

I need to solve the one-dimensional Boltzmann transport equation in a semiconductor numerically, and I want to take a deterministic approach toward the problem (i.e. not use Monte-Carlo or similar non-...
331 views

### How is the bandgap reference diode so accurate? (temperature changes bandgap?)

I am studying about bandgap references (wiki). As a black box approach, (from what I know) it can be seen as a system which gives a stable voltage reference irrespective of the highly varying ...
389 views

### Graded semiconductors - hole concentration function of x

I'm stuck at page 37 of the (second ed.) of "Microelectronics" by Millman & Grabel, section "1-7 Graded Semiconductors". Before that section, it spent some time explaining the phenomenon of ...
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### Discrepancy in introducing Schottky barrier

I have a problem regarding introduction of Schottky barrier in metal-semiconductor junction. Because of this barrier the energies of conduction band vary discontinuously and hence the potential is ...
368 views

### How do I calculate motor efficiency from voltage, current and RPM?

I have a setup where a motor is spinning at a constant (known) RPM, under no load. I know the power going into the motor (voltage * current), and I can find out the rotational kinetic energy of the ...
262 views

### How does electrostatic force affect electronic devices?

How does electrostatic force generated by two seperate plates having opposite charges affect electronic devices? I know that magnetic fields have some harmful effects to electronic devices but I am ...
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### The things to consider when choosing a mesh for an electron detector (MCP detector)

I am designing a electron velocity map imaging setup. I need a copper mesh just infront of the detector to accelerate the electrons towards the MCP detector. I am doing the instrument design for the ...
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### Instrumentation handbook [closed]

Does anyone have any suggestion on a handbook of instrumentation? In particular NIM instrumentation... I would like an approach which will explain the techniques and how to use NIM modules. In ...
148 views

### Is there an equation for the magnetic field of a conductor attached to a magnet?

Let's say I have a hollow conductive rod, 10mm diameter (O.D.), and I place a magnet of known strength 50mm up the shaft. What is the microTesla (mT) or Gauss (G) of the magnetic field (or flux ...
494 views

### Algorithmic approach for applying Kirchhoff's Rules to circuit analysis

Working with Kirchhoff's rules, I am attempting to device an algorithmic approach to finding the unknowns of the problems, I am of a Computer Science background and I am finding it difficult to ...
495 views

### Remote EEG detection / reading

I recently noted that Philips, Accenture, and Emotive grouped together to create a proof of concept that would assist ALS patients to gain greater control of their lives through brain, voice, and eye ...
2k views

### Are there any radiation emitted from the cameras? [closed]

Do modern video cameras emit any kind of radiation? If so, what range of frequencies they have? I was wondering if we can detect any radiation so any help regarding detection will also be appreciated.
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### A logic question on binary variables

I recently purchased some nightlights with sensors. The sensor will make sure the nightlight will only be tuned on in a dark environment. Let's assume the sensor is binary, ON or OFF. Here is the ...
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### 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 ...
108 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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### What stored charges do in a capacitor? [closed]

Why does a fan need capacitor? Capacitor is just providing charges to fan but it can be accomplished without it by directly connecting fan with electric supply. Which other appliances need capacitor?
246 views

### How do you convert RGB lux into a singular value? [closed]

I'm trying to understand the output from an RGBW optical sensor. According to the specification for the sensor this outputs lux. I was hoping someone could explain how the 3 RGB lux values relate to ...
3k views

### How do Zener diodes work?

I was going through some of the theory behind Zener diodes. I know what they're used to work at constant voltage, but I don't know how they work. Actually, I kind of get that too, I know that voltage ...
12k 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 ...
274 views

### Waveforms for a given ideal inverters circuit

I have the following circuit. All the inverters are ideal CMOS. I need to draw the waveforms for each point (A, B, D, E, Vo), given that waveform at input. What I want to ask is if what I did so ...
394 views

### The diode of the lowest voltage

Which diode (semiconductor material) has the lowest voltage in the direction of conductivity?
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### Can we “use” a capacitor while simultaneously charging it?

I know that capacitors can be charged to work like a battery . But I wanted to know whether we can charge a capacitor while it is in use ( given that the current supplied to it is more than what it ...
34 views

### Why does this magnet not damage electronics?

The "magic cellphone holder" found at this link works by taking advantage of a magnet and a metal plate that you stick to your phone. Why does the magnet not damage the electronic components of the ...
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### Do oscilloscope have a lifetime? [closed]

The electron gun in an oscilloscope is, from what I understand, analogous to the one of a Cathode Ray tube. It is made of a material that emits electrons via thermionic emission. Doesn't this slowly ...
254 views

### why do we need a diode in a circuit? [closed]

i know that a diode allows electron flow in a single direction.But doesn't this happen in a circuit even without a diode (for dc source). then why do we need a diode.
2k views

### Determining energy stored in capacitor and inductor in RLC circuit

I've been stuck on the following homework problem for a few hours now with little progress. As you can see, it's a relatively simple RLC circuit with a couple independent sources and a voltage-...