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Questions tagged [electrical-engineering]

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Ohmic resistance in depletion region

Well the depletion region has some ohmic resistance and it becomes hard for me to balance the diffusion net force with the electrostatic net force in zero bias condition.Any help?
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Can anyone help me to clear some questions about diodes and transistors?

i don't understand the basic of the working of diodes, because i imagine that if we have a n-p junction and we want to pass current through from side of n region to p region, if we beat the potencial ...
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1answer
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What is energy band gap?

Explanations for graphene's high electrical conductivity often discuss energy band gap. What is energy band gap and how does it relate to the conductivity of a material?
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44 views

Why does current not increase when the voltage increases in this case? [migrated]

When talking about BJT transistors, a very common graph is the one shown below, that plots (VCE,IC) as an ascending function. As far as I know, the BJT manages VCE so that IC is beta times IB, being ...
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1answer
37 views

How to calculate total power generated?

I have a circuit with a piezoelectric transducer which converts mechanical energy to electrical. The ceramic is connected to a 1 Megaohm resistor and a voltmeter which reads voltage. If I want to ...
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1answer
19 views

Quantum tunneling in zener diodes

Well Zener diodes operate as a voltage regulator because of the Zener effect-Quantum tunneling . Quantum tunneling is the effect when an electron faces an energy barrier but after the energy barrier ...
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27 views

How does a power amplifier works? Does it change the shape of the output signal? [migrated]

I was doing some experiments and I had to put in input a 2V sinusoidal signal at 20Hz through a power amplifier and I got in output an overloaded square signal at +15/-15V at 20Hz. Is it normal? I ...
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3answers
76 views

RC circuit discharge while being connected to a battery?

I am facing a conceptual problem in analyzing the following situation which was part of a physics exam; A series RC circuit with $R = 200k \Omega$ and $C = 10 \mu F$ is connected to a 5V battery and ...
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2answers
60 views

Multiple frequencies [closed]

could someone please inform me how it is possible to send multiple frequencies down one wire? I’m referring specifically to a communication protocol known as HART. It seems they send a 4-20mA signal ...
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1answer
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Which types of collisions contribute to electrical resistivity?

Do electrons only bump with other electrons in a circuit and that only causes resistance? Or do they bump with the nucleus as well? Here's a post I have been studying recently: The path of a ...
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Why does nMOS using N+ gate have lower Vth than nMOS using P+ gate ? (w/o band diagram)

I understand it from band diagram.(Band bending is more stiff in N+ gate case) However, I don't know what's essentially happening. If P+ gate and N+ gate have same dose, their poly depetion will be ...
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2answers
65 views

Difference between diode and LED

What is the difference between a diode and a led? I know a led is a diode and I know how they are used and so on but I'm not really sure why a regular is not also light emitting. Therefore, what is ...
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1answer
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What does the phase discriminator portion of the Costas Receiver do mathematically?

What does the phase discriminator portion of the Costas Receiver do mathematically? The output of the $I$-channel is $ \frac{1}{2}A_C \cos \phi \, m(t) $. Which means for small deviation of phase $ \...
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1answer
67 views

How do I connect a four way key in a potentiometer?

How do I connect (which wire to which terminal) a four way key to a Potentiometer to compare the EMF of two cells. Circuit diagram and a four wayway key is shown in the pictures.
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1answer
43 views

Is a radio receiver antenna a capacitor?

I think so, but its capacitance should be very small, so how can the antenna correctly receive the signal, the low capacitance wont bother the signal?
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1answer
35 views

Why can I hear the treble sounds through a speaker, such as on my phone, better than I can with headphones?

I'm not sure if this is related to my hearing loss, or if anyone else has noticed it, but I find it easier to hear higher frequency sounds coming out of a speaker that I hold up against my ear versus ...
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1answer
29 views

How does a sound box amplifier work?

I read in a few places that in a guitar for example, the vibrations are passed through the connectors to the wood and the wood with its bigger surface is more efficient as a coupler to the air, ...
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2answers
45 views

Principle of potentiometer

I could not understand why the emf of the main cell (labelled E) in the circuit (can be a battery eliminator) should be greater than the emf of the cells (E1 and E2) used in the secondary circuit. ...
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1answer
35 views

How to calculate the dispersion parameter of a Fiber?

I am writing a presentation about DCF Fibers. From many articles i am reading, the dispersion parameter of Fibers are given. But it is not shown how it has been calculated. For example ,in this ...
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3answers
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Is there a physical limit to memory reading and writing speed?

Is there a limit to the speed at which a memory, quantum or classical, can be read or written into? I've seen this interesting question : Is there a physical limit to data transfer rate?. Here I'm ...
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1answer
30 views

How would a square waveform effect an acoustic wave?

I recently did an experiment where I tried to measure the properties of an acoustic wave by using a microphone and speaker in a tube. I was wondering how would changing the waveform to a square change ...
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1answer
37 views

How do multi-meters measure capacitance?

Many multimeters have the ability to measure capacitance along with the ability to measure AC voltage, DC voltage, current, resistance ... The only equations I am aware of that determine capacitance ...
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2answers
43 views

Need of LED Modulation

I have an experiment of calculating the velocity of light by using phase difference produced (link of the experiment is at the end). The experiment has a control unit which has an LED installed to ...
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0answers
45 views

What is the uncertainty on 50 Hz a.c.?

We are doing an experiment to measure velocity using the ticker-tape timer which runs on a 50 Hz a.c. 12 V power supply. I am in Ireland. So the time interval between each pair of dots is 0.02 s. But ...
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0answers
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Why the product of hole and free electron density is constant in semiconductor?

I have learned from a text book of electronics that the free electron density, n (which is equal to that of hole, p) of intrinsic semiconductor due to thermal excitation is a function of temperature ...
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2answers
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1answer
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DC Battery Charging Question

I have a 7.4v LiIon that hold 1450ma. I have a variable DC bench power supply that I can crank up or down and adjust as needed. I want to quickly charge the battery and noticed if I adjust the ...
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2answers
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Grounding secondaries in isolation transformer

In an isolation transformer (I assume a 220v-110v step down transformer is also called an isolation transformer), you can ground either of the secondary leads. I'd like to know the following: If you ...
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1answer
29 views

What does ground in low voltage electronic circuits mean?

I have been confused a lot by the word "Ground". The ground that I've usually heard about is connecting a wire of appliances with the rod buried under earth but what does the word Ground mean when it ...
2
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0answers
34 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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1answer
12 views

What influences the variance of signal transmission speed?

I'm currently thinking about the various sources that influence time when it is synchronized with the NTP protocol. One of them is the physical layer (OSI-model). When sending a bit over a cable, ...
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1answer
23 views

How do scintillation detectors work, for gamma ray spectroscopy

So I understand what happens in the crystal with respect to the interactions and how the electrons in PMT are multiplied by hitting dynodes etc. But what I can't really seem to find any information on ...
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1answer
48 views

Bjt configuration

In common base configuration,we know that alpha is almost 1 which means that the base current is almost zero.But what is the physics behind this base current almost equal to 0?And similarly in common ...
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1answer
50 views

Ohm's Law in Practise [closed]

When the AUX pin of a stereo is connected to my mobile phone's audio female port, I just measured the voltage at the end of this AUX pin (No load is connected) approximately 2mV using a DMM. But when ...
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3answers
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Confusion about how an electron gun works

I'm a little unclear about the charge balance aspect of an electron gun. Referring to this diagram and similar diagrams I've seen, what I don't get is wouldn't the target of the electrons have to be ...
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1answer
67 views

Why we don't utilize most of the radio or microwave spectrum?

WiFi is from 2400-2500MHz or from 5000-5100. Fm Radio is 87-108Mhz, Phones : 450-3400Mhz But most of the spectrum is "wasted". For eg - Why we don't use above 5Ghz?
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1answer
67 views

Potential difference between two points

Okay so this might sound kinda stupid but I'm new to electrostatics and I was doing a question that asked me to find the potential difference between two points . Now I calculated the potential at the ...
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1answer
27 views

Electrical potential with a combination of bodies

1) what would occur with respect to electrical potential if a +1 charged body is brought close to a -2 charged body? 2) a positively charged body next to an earthed conductor For the 1st one I'm ...
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1answer
211 views

What happens to potential when a charged body is placed next to an uncharged conductor?

I know that the potential of the charged body decreases due to induction however I feel as though I need a more in depth answer. Why does induction cause the potential of the charged body to decrease ...
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1answer
37 views

Problem regarding phase difference in Transmission lines

In order to find impedence variation in Transmission line(T.L.) we usually draw Smith chart(it is a complex reflection coefficient ($\Gamma$) plane on which constant resistance and reactance circles ...
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1answer
81 views

Realistic for intelligent undergrad to build low cost muon scatter detector?

With a budget of under $2000USD, would it be possible for an undergrad student to build a muon scatter detector (drift tubes or another method)?
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0answers
24 views

What is the voltage requirement for glow discharge of a hollow cathode?

I'm trying to build a remote plasma source for a dusty plasma experiment. The key thing this needs to do is operate at 1 millitorr Argon gas. To keep it simple, I'm just putting a glass tube on the ...
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1answer
56 views

Who controls completing the circuit in a transistor? [closed]

Consider an npn junction. The p-type semiconductor p has holes which are filled by electrons provided either by the n-type or by phosphorous dopants. The transfer of charge from n to p forms a ...
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0answers
68 views

Using lock-in to measure $ f $ instead of $ f' $

What I know about lock-in measurement is the following: you have a device you want to test and instead of giving it a DC input, you would modulate your DC input with some sinusoidal modulation and ...
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1answer
34 views

Alternator wear due to bad battery [closed]

I recently heard that a bad car battery (I assume "bad" means it drains faster than it was designed to) will wear out your alternator faster. How is this possible? Please note I am not looking for ...
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1answer
20 views

Piezoelctric Ceramic Transducing Capabilties

Piezoelectric ceramics are able to work as transducers, outputting electrical energy when mechanical stress is inputted. However, most ceramics have high static voltage and low current and power ...
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2answers
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How does the centre tap of a **centre tap transformer** at zero volts?

As per my knowledge, the secodary coil will have one terminal at positive and another 0(zero) at one instant, and at another cycle, the other terminal becomes positive and the first one become 0(zero)....
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0answers
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Predicting decay time of a resonant bandpass filter?

In a typical resonant bandpass filter, resonance is set as none at 0 and full at 1, such that the filter rings infinitely at 1 and not at all at 0. If there is a two-pole resonant bandpass filter, ...
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1answer
152 views

How does base-emitter voltage affect the current gain of a transistor?

I'm doing a Physics project related to transistor operation. My data shows that as the base-emitter voltage drop increases, the current gain of the transistor rises and eventually plateaus at a ...
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1answer
26 views

How does the charge on the battery terminal behave?

I am sitting in a train with a car battery of of twelve volts...its positive terminal is connected through a bulb to the metallic body of the coach which is connected to the rails underneath.how will ...