Questions tagged [electrical-engineering]

The engineering discipline concerned with the study, design and application of equipment, devices and systems which use electricity, electronics, and electromagnetism.

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Why bridge rectifier circuit is widely used to make power supply? [migrated]

Why bridge rectifier circuit is widely used to make power supply?. which is better, bridge rectifier with capacitor or without capacitor?
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What can I give as an example for a dumb instrumentation system? [closed]

I've searched through many websites and textbooks but none of them have given an example for a dumb instrumentation device.
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Why are most solar panel rated at 12 volts or 24 volts? [closed]

Most solar panel come in 12 volts or 24 volts, why?
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Exercise with full wave bridge rectifier [migrated]

I study an example of youtube video https://www.youtube.com/watch?v=Kl8IOESVWlM an i want to make transfer function vo = f(vi) when i use the piecewise linear diode model. I worked with the following ...
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Is it possible to create a laser pointer with adjustable beam width?

Is it possible to create a (line) laser pointer with adjustable beam width? I mean instead of having a dot laser pointer, create one where one may press a button to switch from 10m line beam to 5 m ...
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If loads are perfectly balanced, and line resistances are zero, is ground wire redundant?

Here is my understanding of neutral and ground: The return current through the neutral wire is the vector sum of three phase power. If loads are perfectly balanced, the vector sum is zero, and the ...
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Is this actually a Group II, Group IV transistor? What should its properties be?

This question is for more than a theory. I would like to disprove that what I'm working on is not a Group II, Group IV transistor. I know they CAN exist. I don't know why they don't exist or what ...
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Can you use the water flow exiting a hydroelectric generator to generate more energy?

In videos of hydroelectric generators I often see that the water that exits a turbine is still moving with significant velocity. Example of a turbine that has exit water flow with significant velocity:...
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Is there any difference between charge-transfer insulator and conventional (band) insulator?

Like conventional (band) insulators, is conductivity in the charge-transfer insulator blocked by the Pauli exclusion principle?
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Uncertainty of output current in voltage-current converter

I have a problem comprehending some things about uncertainty in electrical measurements. Here is illustrative example from my textbook. We use voltage-current converter for measurement. U1 = 10V, I2 =...
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Physics basics of junction termination structure (JTE)

I have come across two books that try to explain how a junction termination structure work (low doped implant of the same type as the cathode/anode depending of the substrate type). Both books explain ...
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1 answer
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Penning Trap Anode

I am looking to confirm my logic around how the anode in a Penning trap is able to reflect/contain protons via an electric field. My logic is that the anode is an excitinged metal such as (Metal)2+, ...
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Conceptual doubt about voltage drop in a diode

In the given circuit, I am not sure how to solve it, I know that due to the current the diode is in reverse bias, hence no current should flow through it, But the answer is not given that and a finite ...
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Lamp specifications

So when a lamp has a specification of 24 V, 5.0 W, does it mean that it requires at least 5.0 W to work? Can it still consume more power? Or would it then fail? If for example a power supply has ...
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Does voltage limit the magnetic force of a coil?

My question I had is whether it is strictly current that creates the magnetic force in the coil or if voltage is also relevant? The reason for this question is because I figure if it is just current ...
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39 votes
7 answers
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How do headphones and earphones produce good bass if tiny speakers can't produce low frequency sounds very well?

It's a well known fact that small/tiny speakers cannot produce low frequency sounds very well. Conversely, large speakers cannot produce high frequency sounds very well. Hence the need for tweeters ...
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Does a low resistance make it difficult to run a generator?

Imagine I have a simple AC generator. I am providing energy to rotate the coil, which converts this to electrical energy. If I connect the ends to an electrical component such as motor, bulb, the ...
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How does electrical energy in parallel work out?how does less energy travel through more resistance,and lose the electrical energy which it not had? [duplicate]

Before asking my question,I want to talk about certain points 1.Lets suppose there is a battery of 12 volts,this means that the potential difference between the negative and positive terminal of the ...
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What happens during under-modulation?

I need clarification regarding what exactly happens to the information in amplitude modulation if it is under-modulated. I know that if it is over-modulated, some information will not reach the ...
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Rigorous book (or other materials) on Circuits, Electronics etc

What I usually find in a typical book on these topics is the following structure: "Here is the theorem/fact/formula, here is an example - now go ahead and apply this to some trivial problems that ...
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How to model the state space matrix of a pendulum?

Here's an image of the problem: I'm trying to put the following problem in matrix form (state space) but I don't know how would I put -(g/L)sin(x1) in the A matrix since the x1 value is inside the ...
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Why is the relation between voltage ratio and frequency a linear one in a lumped transition line?

In an experiment the cutoff frequency of a lumped transmission line is determined by measursing the ratio of the output/input voltages. The lumped transmission line is a ladder network of 40 ...
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What is the relationship between driving point resistance and Thevenin resistance?

Thevenin Theorem A linear, active, resistive network which contains one or more voltage and current sources, can be replaced by a single voltage source $V_T$ (the Thevenin voltage) and a series ...
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1 vote
2 answers
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What is a realistic value for the internal resistance of an ammeter?

As I understand, ideally an ammeter will have zero resistance as it is connected in series with the circuit and so there will be no potential difference across the device. However, in reality there ...
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How do electrons flow in a "random single wire antenna" of a Raspberry Pi, which is DC and just have one path? (no gnd)

I have been amazed by the fact that just by inserting a cable in a GPIO of the raspberry pic acts like an antenna, as far as I know, electromagnetic waves are generated when there's current, and also, ...
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Why does current reduce in step up transformer?

I have researched about it and found the laws everywhere as if lawyers have written those answer. I know the law of conservation of energy, but I don't want to think like a lawyer, I want to think ...
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Which electric power transmission line has more losses an AC or a DC?

For the same generated and transmitted RMS value of power from an electrical power plant station, which transmission line used, assuming having the same wire specification (i.e. wire material ...
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Would this theoretical battery be practical: 2 charged objects close to one another? [closed]

Consider a system which stores energy by forcing two charged objects (of the same charge) close to one another. When the energy needs to be used, a latch could open and the objects would accelerate ...
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Potential difference in dipole antenna :

Can some one explain this concept in dipole antenna that how potential difference is working? And it is correct to say when connected to the ac source positive charges move to one pole and negative ...
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Using ham radio to communicate with an underground crew [closed]

In "Stranger things 3" Dustin uses a ham radio named Cerebro (an image https://www.reddit.com/r/StrangerThings/comments/fhrdml/will_cerebro_make_an_appearance_in_st4/) stationed on a hill ...
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Relation of electric permittivity $ε_{0}$ and magnetic permeability $μ_{0}$ of vacuum space with capacitance $C$ and inductance $L$ of matter?

I am asking if the permittivity and permeability constants of vacuum space controlling propagation speed of electromagnetic energy, light, through vacuum space: $$c=\frac{1}{\sqrt{\varepsilon_{0} \mu_{...
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Which is more accurate, a quantum gyroscope or ring laser gyroscope?

I can't find any source which says whether quantum or laser gyroscopes are more accurate. I'm also wondering what the advantages and disadvantages are of each technology.
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1 answer
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Removing $1/f$ noise with lock-in-amplifiers

On the Wikipedia page for 1/f noise (at the bottom of the page) it suggests the noise can be reduced if the signal of interest is at DC. DC signals suffer from significant 1/f noise, so one method of ...
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Is there anything other than Resistance, Capacitance, Inductance in a circuit? [closed]

Resistance, Capacitance and Inductance measure certain electrical property of some matter. These term have even given rise to objects like resistors, capacitors and inductors respectively. Few ...
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Shouldn't we take square of the electric field induced inside the dielectric due to electric field applied (as opposed to how it's solved in image)?

Formula used: $ \textrm{Energy} = \frac{1}{2}\epsilon \int E^2dV$ in the image here. If my assumption of finding induced electric field is correct; then will the amount stored energy depend upon ...
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3 votes
1 answer
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What oscilloscope spec to use?

I want to measure a pulse signal using an oscilloscope. The expected rising edge of the signal is in the 1 to 5 ns scale. I have a 20 MHz oscilliscope. Is it correct that the rising edge of the ...
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Moving loop in stationary magnetic field

So according to my understanding, the emf at time $t_1$ and $t_2$ should be the same. However at $t_3$, although there is no emf from induction, there is motional emf, which induces a current. So how ...
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1 vote
1 answer
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Why does the diode in this AC circuit activate when $u1(t)$ reaches specifically 3.5V? [closed]

In this circuit I am supposed to create the graph for u2(t) where u1(t)=5*sin(314t) V. I understand how to get the amplitude of u2(t) and that u2(t) equals the voltage over the 100 ohm resistor when ...
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Over what distance might this device be able to interfere with car radios?

I've been reading recently about a mysterious and possibly hokey medical device of the 1930s. It was a variable-frequency radio emitter, invented by a Dr. Rife, which was supposed to kill various ...
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Why doesn't my phone scroll if I put a ring flat on the screen? [closed]

If I place a ring on the screen of my phone, and then try to scroll with my finger inside the ring, the ring and my finger move up and down, but the screen doesn't scroll. If I leave the ring on the ...
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2 votes
1 answer
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What's difference between Watt Electric ($\rm We$) and Watt ($\rm W)$?

So, I'm learning about Radioisotope Thermoelectric Generator (RTG), and wherever I read about it (in websites, in textbook [Fundamentals of Nuclear Science and Engineering]), the unit used for its ...
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1 vote
2 answers
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How much energy was used to charge the inductor? Electrical systems question

I am a math major, and I am taking a mandatory class that looks more like physics and the professor gave us an assignment with a question that I don't have any idea on how to solve it. The question is ...
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3 answers
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The effect of temperature on Coulomb's law

I have read a sentence in an electrical engineering article but I couldn't understand it. It said: on Earth Temperatures around 150 million degrees Celsius are required to overcome Coulomb's law. the ...
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Why cannot electrons constitute base current in an NPN transistor, but only when combined with holes of P side?

Several textbook's introduction to base current Ib in an NPN transistor is like "As the base is lightly doped with P type impurity, the number of holes in the base region is very small, and, ...
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1 answer
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How effective are privacy screens at blocking blue light in the presence of other protective measures?

For quite a while, I've been using privacy screens, which not only increase... well, privacy, but also purportedly block blue light. However, web search results generally yield very broad statements ...
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1 vote
1 answer
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How do devices control how much power they use?

In power systems (Australian for reference) the grids run at a constant voltage of 220V. I’ve heard of switches were less voltage being used is created by adding more resistors for example to dim ...
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33 votes
5 answers
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How is data transferred between devices?

If you send a text from your phone to your friend, do electrons move from your phone to your friend's phone? How is text transferred (physics wise)? I am a programmer and I want to know how it is ...
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1 vote
1 answer
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What is the wavefront quality of VCSELs? How does the wavefront quality of VCSELs compare to Fabry-Perot laser diodes and DPSS lasers?

I am currently looking at this VCSEL. According to the datasheet, it has a narrow spectral linewidth and emits a Gaussian beam, which are both properties that I find interesting. But I'm also ...
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1 answer
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Error in thermal time constant from measurement

I would like to know how to calculate the error in thermal time constant ($\tau$) based on temperature measurements. For example, lets say I have a plate with a thermocouple and I provide it with a ...
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How to experimentally verify, if the intensity of light from an External Cavity Diode Laser (ECDL) is shot noise limited?

I have an ECDL and i want to experimentally verify if it is shot noise limited or not. Any reference will be helpful.
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