Questions tagged [electrical-engineering]

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20 views

Static Attachment [closed]

How could I get stretch wrap to stick to paper or toilet paper type material? I have a stretch wrap machine that shrink wraps large rolls of paper, and the current method of attaching the stretch wrap ...
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0answers
7 views

How to design over voltage protection Crowbar Circuit? [migrated]

I'm designing a Crowbar over voltage protection circuit with following specifications, Maximum input voltage - 30V Maximum input current - 5A Output voltage - 5V Output current - 5A So I have ...
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0answers
24 views

The physics of microwave vacuum tubes

I've searched this extensively, but I couldn't find anything (the only thing I found was this one). I know this question seems to be more of engineering than physics, but I've found some engineering ...
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1answer
5k views

Shockley's diode equation

We owe a debt to Bell Labs with Shockley, Bardeen and Brattain for inventing the semiconductor. All have now passed on. I remember seeing my first transistor radio in the early 60's. Shockley ...
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0answers
10 views

$C$-$V$ characteristics of MOS capacitors for different material [closed]

For C-V curve below for 3 different materials, (Si, InAs, InSb). What material will be corresponding to curve A/B/C? My understanding is that C is inversely proportional to the dielectric constant in ...
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2answers
112 views

In the electrical circuit/fluid analogy is there an analogy for power loss across a fluid resistance?

For the fundamental passive $RLC$ electrical circuit, analogies are often used to describe the physics of fluid flow where $L$ represents the inertance analogous to inductance, $C$ is compliance ...
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1answer
814 views

Electrical flow in a simple parallel circuit

I'm having trouble understanding something in one of my text books: Let’s have a look at the implications of each circuit configuration. Figure 3.13 shows the Conventional representation of a ...
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1answer
57 views

What causes changes in frequency in the Nation Grid electricity supply? [duplicate]

Following the power cuts in Britain this week, we were told that lack of power being generated led to a drop in the AC frequency as shown in this graph: I understand why a stable frequency is ...
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0answers
17 views

Why to use non-inductive resistances in Callendar-Griffiths bridge?

Worsnop in his Advanced Practical Physics for Students states that All the resistances should be 'non-inductive', for in this method it will be seen that the galvanometer is permanently connected ...
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0answers
15 views

Practical Transformer output

I am a junior on Electrical engineering, on one of my experiment, I have yet found any explanation for this: Is there any possibility that a practical transformer would produce a zero real power on ...
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1answer
276 views

About The foxhole radio: coil rotation times, whether capacitor's needed

I recently tried to make a DIY foxhole radio. Althogh I made it according to the manual (140times coil rotated, ground(220V), blued razor blade, pencil core and antenna (just a steel stick about 1 ...
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1answer
100 views

5G networks and health concerns

Are there any peer reviewed journals on 5G networks and health concerns? I know very well that 5G radiation is of low frequency and non-ionizing and some concerns are related to the power of the ...
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1answer
35 views

Modelling behaviour of a transformer

I'm looking for a physical-mathematical model to describe the behaviour or working point of a power transformer in dependency on its most critical parameters like oil temperature/heat dissipation, ...
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1answer
59 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 ...
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2answers
223 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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0answers
21 views

Why RMS for average voltage in AC current? [duplicate]

We write rms formula as $$v_{rms}=\sqrt\frac{\int_a^b[f(x)]^2dx}{|b-a|}$$ I know if we take arithmetic mean average voltage will be 0. So we want all voltage values to be positive. Why don't we do ...
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1answer
170 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
24 views

Half wave rectifier confusion

I am searching for a good book or link or video that might give some fresh idea about half wave rectifier properties I mean in my book prescribe by my university that has introduced some of the basic ...
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1answer
31 views

Question about the purpose of a transistor [closed]

I've been studying about diodes and transistors and something made me wonder about the purpose of transistors. In the examples we were talking about increasing current by using two batteries with a ...
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1answer
364 views

Why is voltage gain highest in common base transistors whereas lowest in common collector transistors?

Although the common base transistors have current gain lowest and the common collector transistors have current gain highest.
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1answer
82 views

Why do we have to switch off mobile phones during flight in airplanes? [closed]

During take offs the flight attendant makes sure that mobile phones are switched off (or maybe turned in airplane mode), why is that necessary? (I suspect that there is something to do with physics ...
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13 views

Reverse bias under 0.7V

Assume we have a diode. Well, I was wondering what is happening if we connect the negative terminal of the battery to the p type region and the positive terminal of the n type region to the positive ...
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1answer
30 views

MOSFET Body terminal

What is the point of the body terminal in a MOSFET. If we assume Vsoure=0, Vdrain>0 then we will have a linearly changing voltage from drain to source. Then if Vgate>0 , depending on the difference ...
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0answers
16 views

Reverse bias voltage drop

In reverse bias , when we go up the breakdown voltage why is there a voltage drop across the diode?.I mean the diode does resist to the flow of charges but when the electrons flow inside the diode ...
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0answers
15 views

Diodes normal polarised with voltage below forward voltage

Assume we have a circuit with a diode and a voltage source . The voltage source has potential 0.4V .If we polarise forward the diode ( p type region connected to cathode and n type region connected to ...
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31 views

Why does applying a voltage through the gate on a transistor help lower the potential barrier?

At the potential barrier, all that atoms are "satisfied"; they each have the appropriate number of electrons in their valence shell since the free electrons on the n-type side fill the holes on the p-...
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4answers
4k views

Why should a voltmeter have a higher resistance than of any circuit element across which the voltmeter is connected?

According to my textbook, it is said that, for an ammeter: It is essential that the resistance $R_A$ of the ammeter be very much smaller than other resistances in the circuit. Otherwise, the very ...
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2answers
37 views

Current law explained

Kirchhoff's Current Law (KCL) is experimentally proven but what exactly happens?. I have made a model by taking the drude model and adding the interactions between the electrons and the reason why ...
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1answer
172 views

Reflecting radio waves?

I have a laptop that I primarily use for music. I don’t want to have to bring my laptop to the basement every time I want to listen to music. I have bluetooth headphones and I was wondering if there ...
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0answers
21 views

Drude model for diodes

Well I was wondering how we can apply the drude model for diodes.The normal drude model is used on conductors and insulators and since the diode in forward bias is a good conductor(not the best but no ...
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2answers
58 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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0answers
29 views

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
58 views

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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1answer
73 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
138 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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2answers
619 views

Kirchhoff's laws in phasor domain

While analysing AC circuits, we write voltage, current etc all with complex numbers namely "phasors". While studying the same, I wondered if Kirchhoff's laws held good with current and voltage in ...
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3answers
92 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
119 views

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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2answers
67 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
44 views

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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0answers
19 views

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
114 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
20 views

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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3answers
220 views

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
105 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
56 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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0answers
40 views

What is the optimum altitude for tapping atmospheric charge?

The atmosphere appears to have a large potential difference (voltage) in relation to ground. The obvious example is the thunder where this voltage becomes large enough to break the insulator - air. Of ...
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1answer
430 views

Larsen effect and pitch of sound

Why Larsen effect produces always high pitched sounds, never low pitched?
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3answers
37k views

Why do we use AC for long distance transmission?

Why do we use AC (Alternating Current) for long distance transmission of electrical power? I know that AC is such a current that changes polarity (magnitude and direction) and has fixed poles.
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1answer
42 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 ...