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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Which is better conductor silicon or germanium and why and also which has more band gap and why and what affects the band gap in material?

want to know on what factors energy band gap depends upon.as per me it is due to electron-proton attractive forces but according to this germanium should have higher gap than silicon but germanium has ...
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1answer
22 views

holes in an electronic circuit [closed]

Many times, by looking at electronics circuits I noticed that they have like small holes printed in yhem. The question I want to ask is, what s the purpose of these holes?
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0answers
33 views

Green LED Forward Voltage

Yesterday in lab, we were asked why all of our green LED had large forward voltage than expected. We expected for the forward voltage to be at around 2.1V as according to hf=Egap=eV. Yet, we ...
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0answers
29 views

Can you get a better signal to noise ratio by connecting multiple microphones in series?

From my very basic understanding of microphones, they generate a tiny bit of electricity as the membrane moves, this is the signal. It would stand to reason then, that if I connect a bunch of ...
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7 views

16 Volt on a 12 Volt LM317 Regulated Power Supply [migrated]

I recently purchased a 1,2-12V regulated power supply with an LM317 chip and accordingly, a 220V to 12V transformer. Because I did not need the added functionality of the "logic pen" facilitated by ...
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1answer
43 views

Video recording interference

I'm currently working on an Android App that records while driving in a car. Similar to the popular Dashcams. While developing this App I saw a lot of ugly glitches on my videos. I used a Nexus 5 for ...
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1answer
65 views

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 ...
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0answers
49 views

Why is the satellite dish still needed?

How much does it amplify the signal? The receiver cannot pick up the signal without the dish? Is it possible that it will disappear in 10 years? As the sensitivity of the receiver is enhanced? ...
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2answers
65 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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0answers
30 views

Normalizing temperature data of CPU sensors to ambient

My scenario: I want my application to stop or take some decision based on temperature. say like if my ambient is morethan 41 i want to switch off the application and we do not have an separate ...
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0answers
25 views

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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3answers
112 views

Why is $np$ always equal to $n_i^2$?

For you guys who studied semiconductor physics must be familiar with the equation: $$np=n_i^2$$ I can understand why this is true for the intrinsic case (the broken bonds would always provide ...
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0answers
27 views

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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1answer
18 views

Reducing voltage with resisitors [closed]

I am working on a project in structure, in which i have to rotate the second storey of my building, now my assembly consists of 12 v battery connected in parallel with 12v motor which is connected to ...
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1answer
60 views

Things that must be considered when mass producing a capacitor [closed]

The question is to list four things that must be considered when a capacitor is chosen for inclusion in a circuit which is to be mass produced. Are there a specific set of four things? I've come up ...
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1answer
34 views

Specific heat capacity for solids of changing temperature

I was reading the following post: If the specific heat capacity depend upon the temperature, what formula we should use instead of $Q=mc\Delta T$ and I understand that the total energy needed is ...
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0answers
14 views

Problem in resonant tunneling diode (RTD)

What happen if the two barrier width in RTD are not same? How the transmission coefficient change for this? How the dips are formed in the transmission coefficient graph?
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3answers
75 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 ...
2
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1answer
33 views

How would you read memristor data?

According to many experts; memristors have the potential to change and drastically improve data storage and processing power of computers. But there is one small thing that doesn't fully make sense to ...
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4answers
50 views

What is the potential difference across a disconnected diode? [duplicate]

I think potential difference across disconnected diode should be zero but how? the last graph tells that there is a potential difference between the two ends of a diode. then how can be it zero?
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1answer
57 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 ...
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1answer
47 views

Equivalent DC circuit with charged conductors

I am trying to find equivalent circuit for a circuit composed of interconnected capacitors when isolated pieces of conductor may carry nonzero electric charge, and I have been struggling with this ...
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1answer
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 ...
2
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0answers
20 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 ...
4
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1answer
54 views

Why is 2-terminal sensing less accurate than 4-terminal sensing if the internal resistance of leads is known?

I have a pretty good understanding of 2-terminal vs. 4-terminal (kelvin) sensing measurements. I understand that in the 4-terminal measurement, current is supplied by 2 terminals that are separate ...
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1answer
205 views

How the voltage of a capacitor is changed in charging/discharging [closed]

Capacitors are called fast batteries in electronics. I understand that a battery is charged by a constant current while the voltage is almost constant during charging and discharging. For example, a ...
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0answers
47 views

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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0answers
31 views

Thermistor is more sensitive than metals [closed]

Can anybody tell me, why a thermistor is much more sensitive at temperature variation than a metal?
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0answers
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?
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1answer
23 views

Charge in capacitor after switching voltage

Say you have a capacitor connected to a voltage source (vs). After the capacitor has fully charged, you cut the source voltage in half to vs/2. The voltage across the capacitor should change to match ...
2
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0answers
36 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

Why for each electron – hole recombination, an electron from the negative terminal of the battery is released

Why for each electron – hole recombination, an electron from the negative terminal of the battery enters the N-region and then drifts towards the junction?
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0answers
11 views

Differences between Metal-Bridge-Metal system and Donor-Bridge-Acceptor system

What is the real difference between Metal-Bridge-Metal system and Donor-Bridge-Acceptor system? In MBM there are anchor groups between the molecule and the metal electrode, can’t the groups act as ...
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0answers
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?
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3answers
36 views

Why do electron emits energy in a LED when they transfer from the n type semiconductor to the p type semiconductor

after an electron moves from the n-type into the p-type silicon, it will combine with a hole and disappear. That makes an atom complete and more stable and it gives off a little burst of energy. But ...
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1answer
86 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 ...
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1answer
52 views

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 ...
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0answers
24 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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1answer
200 views

why is I-V characteristics of a solar cell drawn in the 4th quadrant?

My book says because a solar cell does not draw current but supplies it to the load. I don't quite get the explanation. How is it related?
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2answers
35 views

Semi conductors (holes and electrons)

The following relation is mentioned in my text book for semiconductors in thermal equilibrium. $$n_e ×n_h = n_i^2$$ $n_e$ stands for the number of electrons. $n_h$ stands for the number of holes. ...
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0answers
29 views

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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1answer
107 views

Textbook recommendations for electrical circuits and electronics?

I'm a junior physics major focusing on theoretical physics. I didn't take any courses in electrical circuits or electronics (though I did take E&M). Recently I started feeling that this is a ...
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1answer
121 views

Why does the symbol have an arrow? [closed]

What does the arrow in the symbol mean? Does it mean that it is a variable voltmeter and ammeter?
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0answers
22 views

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 ...
5
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2answers
198 views

Why are only Group III & V elements used for doping?

Only group III & IV are used for doping in elemental semiconductors like Si and Ge, why can't other groups be used instead?
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3answers
115 views

How does the tuner really work in a crystal set?

I would like to know how and why the tuner works in a crystal set radio. I already know all the theory and the "formal definitions" (this creates a resonant circuit which responds to an alternating ...
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1answer
92 views

Can conductivity (or resistivity) value be assigned to 2D materials?

2D materials, such as graphene monolayer or graphene nanoribbon, don't really have a cross section. By definition, conductivity is $\sigma = \frac{J}{E}$, and $J$, the current density, is calculated ...
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1answer
46 views

What is the underlying transport mechanism in “ballistic transport”?

From Wikipedia: Ballistic conduction or Ballistic transport is the transport of electrons in a medium having negligible electrical resistivity caused by scattering. Without scattering, ...
2
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1answer
67 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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0answers
243 views

Exact (quantitative) definition of “knee” and/or “cut-in” voltage?

Sort of a 2-part question: 1) I know they are used interchangeably but are the "knee" and "cut-in" voltages of a diode actually the exact same thing? I had thought that the "cut-in" voltage was ...