Questions tagged [electrical-engineering]
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2answers
34 views
Is it correct to say that a smartphone cable is only a “1A” cable?
A store owner said that some lower quality smartphone charging cables are only "1A cables", so if you want 2A, those cables won't do the job.
Is it correct to say a cable is only 1A? Does the metal ...
-1
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1answer
33 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 ...
0
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1answer
23 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, ...
0
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0answers
22 views
Determination of read/write lifespans of NAND drives [migrated]
I check around and there are various numbers for different manufacturers solid state drives as read and write life terms. At the very fundamental level input/output speeds of these devices are pretty ...
0
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2answers
17 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
6 views
BJT as a switch: what am I doing wrong? [migrated]
I'm studying the following circuit
The image is explicit but as you can see the input measured in the upper terminal is a square wave with $E_c$ and $-E_c$ as levels.
Now I also had no trouble ...
0
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0answers
17 views
Capacitors in Amplifiers [migrated]
I am reading about single stage CE Amplifiers and I don't understand how the capacitors work here.
1) Coupling Capacitors:
"The coupling capacitor is used to isolates the d.c. of one stage from the ...
0
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1answer
28 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 ...
2
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0answers
40 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 ...
0
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1answer
29 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 ...
0
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1answer
34 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
33 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
40 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 ...
0
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2answers
56 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?
-2
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1answer
28 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 ...
0
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2answers
44 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 ...
0
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1answer
26 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
25 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 ...
0
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1answer
11 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, ...
1
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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
46 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 ...
-2
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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
818 views
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 ...
1
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1answer
65 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?
0
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1answer
35 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 ...
0
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1answer
26 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 ...
0
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1answer
73 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 ...
0
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1answer
36 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 ...
2
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1answer
79 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)?
0
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0answers
21 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 ...
1
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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 ...
0
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0answers
65 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 ...
-1
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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 ...
0
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1answer
19 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 ...
0
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1answer
52 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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0answers
21 views
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, ...
0
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1answer
117 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 ...
0
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1answer
25 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 ...
0
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2answers
33 views
Will the EM field radius of 10 x 20 Amp wires be smaller than a single 200 Amp wire?
Not sure how the radius is determined but Will 10X20amps wires in one conduit(meaning they are together) EMF radius be smaller than 1X200amps wire?
I'm having a real life question on this: I can run ...
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0answers
30 views
How to mesure the axial induction factor of a small propeller using a DC motor?
I am trying to measure the axial induction factor of a small aeromodelling propeller.
By axial induction factor I call the ratio of the velocity of the wind far from the propeller $V_{\infty}$ over ...
0
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0answers
13 views
Edge Effects of an Ideal Diode
The ideal diode equation says that current changes in the quasi-neutral region as you travel across the axis. However, how do the surfaces on the perpendicular to the to flow of current affect the ...
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0answers
31 views
Headphone NFC (Near Field Communication): Why is range limited (for a physics layman)?
I have an headphone which uses NFC for pairing (Sony One Touch - I think it is active NFC). My question regarding NFC is: Why is the distance for my pairing mobile phone limited to 1,5 cm length for ...
0
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0answers
24 views
Would thermophotovoltaic cells or thermionic converters be most effective for creating 5MWe from a nuclear reactor in space?
Assuming that the working coolant is a NaK and Li-7 mixture heated to 800 degrees Celsius, would a thermionic converter (as used in the SNAP-10A reactor) or a thermophotovoltaic cell1 serve as the ...
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1answer
68 views
How can I negatively charge a metallic surface? [closed]
I wish to negatively charge the surface of a fan blade in a ceiling fan. As the fan is connected to AC power, it is safe to assume that we have electric power at our disposal. Also this surface needs ...
55
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3answers
8k views
Is there a physical limit to data transfer rate?
Is there a physical limit to data transfer rate (e.g. for USB $3.0$, this rate can be a few Gbit per second)? I am wondering if there is a physical law giving a fundamental limit to data transfer rate,...
1
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1answer
74 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
23 views
Action at distance with charges (Electromagnetism) - help please!
My professor taught us in a theory lecture on electromagnetism , that if two charges are 1 light year apart and the charge on the left moves towards the charge on the right. The force felt on the ...
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1answer
214 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.
0
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2answers
99 views
Most Effecient Railgun Design [closed]
This is my first post on this forum. My name is Kavika and I am a high school freshman.
For a school project, I am designing and engineering a functional rail gun. I am on a budget and am wondering ...
