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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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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68 views

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?
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7k 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
230 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 ...
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390 views

The diode of the lowest voltage

Which diode (semiconductor material) has the lowest voltage in the direction of conductivity?
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1answer
521 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 ...
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1answer
147 views

Am I solving this basic Kirchoff's current law and Ohm's law problem correctly?

After moving onto some of the practice textbook exercises in the section covering Kirchhoff's current law and Ohm's law, I came across a problem which evades my best attempts at solving it. Using ...
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874 views

Dependence of intensity of a LED on forward bias voltage

Due to increase in forward bias voltage, the intensity of light increases but after a particular value the intensity decreases. Why?
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2k 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 ...
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1answer
408 views

Why cellphone cameras don't have optical zoom

I have just basic understanding of Physics from elementary school. But I still wonder, why after 10 years of cameras in cellphones, there is no "small-pack" optical zoom. I think there should be no ...
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1answer
223 views

Full wave rectification [duplicate]

In the construction of a full wave rectifier, why is there central tapping in the secondary winding of the power transformer? What's the pure reason behind it? If there was no central tapping, what ...
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1answer
4k views

Characteristic of a common emitter transistor [closed]

How is Base emitter junction and collector emitter junction biased? How do we determine the value of potential difference between emitter and collector required to be maintained in order to determine ...
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1answer
214 views

Horsepower achieved with multiple motors

Scenario I'm planning to build an electric motor for fun (not for any practical purpose). I recently purchased a shapeoko CNC mill kit and intend to manufacture most of the parts housing, stator etc. ...
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1answer
100 views

Factors on which barrier potential in a p n junction depends

I have a few queries regarding the barrier potential in a p-n junction diode. Is the barrier potential dependent on temperature? Why/why not? Does the barrier potential depend on doping ...
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1answer
43 views

portable transistor radio [closed]

I recently bought a cheap (@ US$7) transistor radio, with an FM band, an AM band, 4 SW bands, and 2 VHF (tv audio) bands covering channels 1 to 13. However, i later discovered that i couldn't tune in ...
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1answer
76 views

Analyzing the voltage output of clampers

Let us say that we have the following negative clamper circuit with a 50 volt peak-to-peak square wave as an input: The output from the circuit is a -50 volt square wave with the peak positive ...
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1answer
85 views

Is a motor HP torque directly proportional to the increasing HP among identical motors?

Say you have three motors: Motor 1 = .10 HP with x torque, performing task A Motor 2 = 1 HP with y torque, performing task A Motor 3 = 10 HP with z torque, performing task A If the motors are the ...
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1answer
147 views

What's wrong with this solution to freshman textbook example for Ohm's law and Kirchhoff's current law?

I'm a freshman taking an introductory course on circuit theory and I've run into a bit of trouble working through a textbook example practice problem. Unfortunately, it only lists the answer and not ...
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1answer
90 views

Increasing potential in a voltage doubler

When I use a sinusoidal input AC-voltage from -1 Volt to +1 V , the potential between the diode and the capacitor is increasing. But why do I reach a value of 2 Volt over the diode? I deliberately ...
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1answer
3k views

PN Junction Depletion Region

So it took me a little bit to understand this, but I want to make sure I have a few things right. First of all, when a Crystal Structure with One side N-Doped, One Side P-Doped are in the same ...
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2answers
809 views

Explanation for transistor as amplifier

In transistor as an amplifier, we have NPN transistor (base in the middle and emitter and collector at the sides). The collector has electrons in majority because it is N-type. similarly, holes are in ...
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1answer
360 views

Is it possible to make an RFID-like device which responds to a metal detector?

Would it be possible to make a small device which can be easily detected with a metal detector (or similar) from several feet away? It would need to operate kind of like a shop-security tag but it ...
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0answers
10 views

Questions on Ruhmkorff coils [migrated]

An availability of spare electronic components at my home and a project that is due next week has led me to wonder about making a Ruhmkorff coil that can produce good sparks. However, the traditional ...
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21 views

Is it possible to raise the voltage of a power source by lowering its current indefinitely (i.e. transformers)?

Let's say you have a D battery. You wire it up to the primary of a step-up transformer, which you then in turn wire up to another step-up transformer,...etc. Is there a limit to how high the voltage ...
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0answers
9 views

Dependence of $I_s$ on $T^x$ in a p-n junction

So we have the current through a p-n junction characterized by the equation $$I = I_s * [\exp(qv/nkT)-1]$$ Concerning the forbidden energy game $Eg0$. $I_s$ is proportional to $T^x \exp(-Eg0/nkT)$ - ...
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1answer
19 views

Why is Al2O3 so popular in plasmonics?

I've tried to find my own solution for this question and found out that It is cheap It is an insulator It efficiently absorbs UV Are there more properties that makes it so popular?
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What is the work-function of a monolayer metal on a substrate with charge redistribution at the interface?

The work-function on subsrate/metal with nm thick (or above) metal layer generally reveal the intrinsic work-funtion of bulk metal. But what if there is a monolayer thick metal, and there is charge ...
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13 views

Electronic device malfunctions from condensate

I'm fairly certain my tablet runs better in a dehumidified sealed compartment. I can't really prove it...but I know my hearing aids perform better after dehumidifying. I asked here and they said a ...
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1answer
13 views

why a charge never converted to energy as it work on other charges by displacing them various times?

When a charge is brought near another charge it exerts force on It...innumerable charges brought near it one by one it attract and displace them by doing work on these charges...which require ...
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2answers
80 views

Would you please explain this statement please [closed]

As the atoms of a material are brought closer together to form the crystal lattice structure, there is an interaction between atoms, which will result in the electrons of a particular shell of an atom ...
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0answers
17 views

Thyristor turn on process.depletion region increases or decrease?

When gate-cathode forward voltage is applied in SCR, according to normal convention, depletion region near J2(middle junction) decreases or gradually increases? If there is any mistake in asking the ...
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3answers
74 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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1answer
72 views

Internal Resistor in a Diode

When we talk about the resistance of a diode (of the P and N region), is this resistance like the one inside an Electro-Motive Force or it acts like a normal resistor (external electric field exist)? ...
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2answers
29 views

Laser beam sensed by scattering

Can a laser beam, whether it is a IR laser or of the visible to human eye spectrum, be seen/sensed by an electronic eye like a photosensor/photodetector, not human eye, if the beam is just in air? For ...
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42 views

How does current flow in the circuit during negative cycle of input?

So,as far as I know the input signal just controls the current from +Vcc as per this analogy But in the first picture during the negative half cycle of the input waveform the output wave form is ...
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0answers
34 views

why do everything tend to be stable? [duplicate]

Whenever I ask'why does a proton attract electron?' People say that 'because they are oppositely charged' But I want to know why do opposite Charges attract each other and tend to become neutralised? ...
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0answers
15 views

What is the effect of doping silicon with an excessive amount of group V donors?

What is actually the effect of doping silicon with an excessive amount of group V / donor atoms? I read it reduces the conductivity but I dont understand why.
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1answer
94 views

Variable Resistance

We know that the resistance increase with temperature or for exemple in an AC circuit, the resistance is superior to the same resistor for DC current due to skin effect. But my question is for a same ...
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60 views

Ohmic contacts in a diode (metal-semiconductor junction) - contact difference of potential $V_0$ - how to compute

I'm reading "Microelectronics" by Millman, Grabel. Premise: The book developed, for a pn step-graded junction, the contact potential as $$ V_0 = V_T \text{ln} \frac{p_{p0}}{p_{n0}} = - V_T ...
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1answer
105 views

What's the difference between tunnel diode (TD) and resonant tunneling diode (RTD)?

According to wikipedia, a tunnel diode is a PN junction whose energies are shifted with bias, while a resonant tunneling diode is a quantum well between a double barrier, whose energies change with ...
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3answers
191 views

Explaining the current flow of the positive shunt clipper (diodes)

I am currently studying clippers or parallel limiters in the Navy and I was wondering if someone could clear up a few things for me. Here is a picture that fits my description: A clipper has a ...
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0answers
90 views

Does the Shockley Diode Equation hold in a dynamic circuit?

Consider the following simple photodiode circuit: I've created a real-life version of this circuit, and I've detected that $I$ is oscillating: $$I(t)=I(t+\tau)\tag{$\tau\approx ...
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0answers
64 views

How can a paper battery behave like a capacitor?

I was trying to understand how paper batteries work and came across some explanations saying that the paper battery can also behave like a supercapacitor on account of its ability to discharge and to ...
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0answers
87 views

Charge Amplifier response and frequency response [closed]

I am getting ready for my final and have completed everything on my study guide except for two questions I cannot figure out. Here is the first question: I have gone through all my lectures and ...
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0answers
33 views

What is the mechanism of conduction of electric current in a conductor? [duplicate]

I am just very much confused about what mechanism is followed when we connect the - terminal of battery to the + terminal through a conductor? What happens inside the conductors that makes the ...
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2answers
294 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
850 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
385 views

Is electronics a core topic in physics? [closed]

I thought electronics is mainly discussed in engineering majors. But in my university Electronics and Digital Electronics is also compulsory for physics majors.I searched other's syllabus, but I ...
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2answers
65 views

What temperature will create amorphous TiSi?

At what temperature will create amorphous TiSi? I think it's around 500 Celsius but I'm not sure.