# Questions tagged [electrical-engineering]

The tag has no usage guidance.

320 questions
Filter by
Sorted by
Tagged with
8 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 ...
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 ...
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 ...
58 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 ...
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 ...
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 ...
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 ...
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, ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
31 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 ...
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 ...
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 ...
32 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-...
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 ...
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 ...
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 ...
60 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?
76 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 ...
141 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 ...
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 ...
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 ...
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 ...
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 ...
125 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 ...
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 \$ \...
106 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.
57 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?
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 ...
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, ...
227 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. ...
60 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 ...
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 ...
40 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 ...
52 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 ...
45 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 ...
60 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 ...
95 views

### 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 ...
86 views

### Why diodes can be used to create a current-independent voltage drop? [duplicate]

How is current independent of the voltage drop in a diode?
30 views

### 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 ...
47 views

### 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 ...
47 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 ...
83 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 ...
14 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, ...