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1answer
25 views

Can Thevenin voltage ever be negative?

So in context of Thevenin's and Norton's theorem, can Thevenin voltage $V_{th}$, as in http://en.wikipedia.org/wiki/Thevenin_theorem, ever be negative? I know that $R_{th}$ can be negative, but never ...
0
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2answers
58 views

Induction on a circuit with switch

I have the following circuit: It is subject to a steady, time-invariant magnetic field which points out of the paper. At $t = 0$, the switch closes. I thought that the magnetic flux would decrease ...
5
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6answers
8k views

What would be the effective resistance of the ladder of resistors having n steps

I'm a tutor. This is a high school level problem. In high school, every one have might have solved a problem of effective resistance of a ladder of resistors having infinite steps. Now the problem is ...
1
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2answers
36 views

How does electrostatic force affect electronic devices?

How does electrostatic force generated by two seperate plates having opposite charges affect electronic devices? I know that magnetic fields have some harmful effects to electronic devices but I am ...
1
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0answers
52 views

Concepts in Gabriel Kron's later papers

Gabriel Kron was an important research electrical engineer known for applying differential geometry and algebraic topology to the study of electrical system. Towards the end of his career he published ...
3
votes
1answer
309 views

How do High Electron Mobility Transistors (HEMT) work?

I am studying High Electron Mobility Transistors (HEMT), but I simply cannot understand how they work in the way described by the references I've read on the Internet. This is what I understand so ...
1
vote
0answers
19 views

Neutral wire capacity [closed]

I have three DC circuits in my solar array. I have a three lead + ground (bare copper) tec armoured cable (#6). Why not run one circuit using the bare ground as negative? In fact, why not run three ...
1
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3answers
321 views

Power transfer in a transformer

Can it be proved using the concept of induced emf that power supplied at the primary coil equals power consumed at the secondary. I tried following. Let primary coil be called 1 and secondary be ...
6
votes
1answer
110 views

Random walks on resistive network

I have been referring to a paper http://arxiv.org/abs/physics/0405135 to determine the effective resistance using random walks for an infinite square resistive lattice Though the author seems to ...
1
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2answers
62 views

Would magnetic flux be necessary for analogous systems?

I learned about the analogousness between mechanical and electrical systems a few months back (with the help of Feynman). Yesterday, my professor was lecturing about this topic, when she told that ...
0
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0answers
50 views

can we get electrical energy from gravitational energy? [duplicate]

Now I'm trying to give an answer of the question. Satellite rotates about earth by the gravitational force of earth. Now if we place the satellite in such an orbit so that it rotate in opposite to ...
0
votes
1answer
18 views

Since Synchronous machines are constant speed machines how are their speeds varying with variation in load?

I understand that the power output depends on torque angle. So how does an increase in torque angle cause the rotor speed to reduce? Aren't the synchronous machines supposed to be running at constant ...
0
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4answers
63 views

Why is capacitor used?

I don't quite get the practical use of a capacitor. The theory is fine, but in simple words please explain how, why and where capacitors are used? Is there any other equivalent circuit for capacitors? ...
1
vote
1answer
87 views

Differential Equations for Block Diagram of Satellite Attitude Control System

I am trying to understand the procedure to setup differential equations from a block diagram. The enclosed example is about the attitude control of a satellite. The ultimate goal is to find a ...
0
votes
0answers
51 views

Circuit analysis, calculating voltage across resistor [duplicate]

i'm solved this question, I'm sure that solution is right, but my instructor says that V1=116V, and also he said that he will not show how he get this result.Please help to identify who is right.
1
vote
1answer
28 views

Optical Waveguides with grating

I have some problems about mode analysis in grating-coupled waveguides,Would you please introduce me a useful book about wave propagation in these structures.
0
votes
0answers
27 views

Rotating neutral for 3-phase system

What does it mean by oscillating neutral for 3-phase electrical system? Is it any effect of harmonic production due to magnetic core hysteresis nature? I have been searched a lot about this through ...
0
votes
0answers
75 views

Reflection & Transmission curves of waveguides

I have simulated a grating-coupled waveguide in Comsol Multiphysics, the waveguide consists of 2 dielectric layers and air as the cover of waveguide. I have excited the modes of this structure by a ...
1
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1answer
38 views

Simulating electrical sublimation of aluminium foil

When i apply high voltage (through a capacitor bank) across an aluminium foil, it gets converted into plasma. I want to simulate this process and study the properties of the plasma produced ...
0
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5answers
3k views

Current through the reverse biased junction in transistor [closed]

A transistor is a three terminal device. One terminal is called emitter, one collector and in between them is base. Now, during biasing the junction between emitter and base is made forward biased and ...
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votes
2answers
10k views

Why is Near Field Communication (NFC) range limited to about 20cm?

Near Field Communication (NFC) operates at 13.56 MHz. Near Field is the region situated at a distance r << λ λ = c/f ...
0
votes
1answer
144 views

Studying Quantum Electrodynamics?

As an electrical/computer engineer, I already have a relatively thorough understanding of classical electromagnetism. From what I understand though, classical EM is only an approximation to quantum ...
0
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0answers
31 views

Transformers rate equation

Going back to transformers after some years I realize they hide a possible missconception I'm not sure I really understand. It is not easy to find a full derivation of the well known relation ...
1
vote
1answer
75 views

How can current be a smooth curve?

The following is a graph of the current across some circuit element: Note how the current is treated like a smooth continuous function. Even in the analysis of things (i.e. analysis of the ...
0
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0answers
50 views

Charge Amplifier response and frequency response [closed]

I am getting ready for my final and have completed everything on my study guide except for two questions I cannot figure out. Here is the first question: I have gone through all my lectures and ...
1
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3answers
704 views

Would connecting p-type and n-type semiconductors work as a diode?

If we placed p-type and n-type semiconductors close enough to be touching (see fig. 1), would this arrangement work as a diode? ...
0
votes
2answers
259 views

How do I combine three resistors which are in parallel with each other?

For this circuit (a and b are connected by a battery), Will I be able to find the total resistance of the circuit by adding resistors that are in series and combining resistors that are in ...
0
votes
0answers
36 views

How do cathode ray tubes (CRT) synthesize colours?

I just read about how LCD displays were based only on black&white contrasts, and only colour filters on each subpixel generated the colour of a pixel. However, how does that happen for a CRT? Is ...
0
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0answers
19 views

How does band narrowing (heavily doping the emitter) affect the alpha F and alpha R in the Ebers-Moll model of a BJT?

I think that when the emitter is heavily doped, the bandgap is reduced which increases the reference forward current(current flowing through the E-B junction ) but the alphas themselves do not change. ...
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4answers
2k views

Transformer: primary side & secondary side current 180 degree out of phase

I am a novice in electrical engineering. I notice that in transformer the secondary side current & current referred to as primary are 180 degree out of phase from each other. But why it is so, I ...
1
vote
4answers
1k views

When does Thevenin's theorem not apply (modelling a power source with a ohmic internal resistance)

Most physics text books say that a power source can be modelled as an EMF with a internal resistance. This is also know as Thevenin's theorem or Norton's theorem. However I have read in some sources ...
4
votes
1answer
557 views

Turn-on delay time for Laser diode

Do you know any simple explanation on the reason why the turn-on delay time on a laser diode is reducing while we increase the bias current? Turn on delay,is the time that the laser needs from the ...
0
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0answers
30 views

P-type MOSFET performance

I was reading somewhere that the (110) plane has the highest atomic density and is best for p-channel MOSFET performance. How high atomic density influence the performance of P-channel crystal?
0
votes
1answer
11k views

What is the role of center-tapping in a full wave rectifier?

Note: I have already tried googling. Although similar questions have been asked on different forums, I couldn't find a detailed explanation, which I could really understand. Circuit diagram ...
0
votes
0answers
180 views

Electric field intensity at the center of a small cavity in a large block of polarized dielectric

I'm having trouble with an exercise in my textbook. The question is: Determine the electric field intensity at the center of a small spherical cavity cut out of a large block of dielectric in which a ...
-2
votes
1answer
29 views

What is the suitable temperature for a motor to work without failing? [closed]

How much body temperature can a motor withstand along with the ambient temperature to work without failing?
2
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0answers
71 views

Fermi Energy and the Electric Potential

In an extrinsic semiconductor the electric potential is: $$\phi = \frac{1}{q}(E_{\mathrm{F}} - E_{\mathrm{Fi}})$$ where $E_{\mathrm{F}}$ is the Fermi energy, $E_{\mathrm{Fi}}$ is the intrinsic Fermi ...
4
votes
1answer
98 views

Magnetic muscles [closed]

Consider two flexible sheets glued at the ends, with electromagnets attached to both of them, so that depending on the directions and strength of currents passing through them, the system could be ...
1
vote
3answers
209 views

Electronic filter

Can you explain, please, step-by-step how an electronic filter does work? For example, high pass filter. I know It's a trivial things, but I can't get it completely. Don't bring me formula and etc. ...
5
votes
2answers
187 views

Could we run an electric car on electric eels?

Could we run an electric car on a tank full of electric eels? I've heard electric eels are around 400 to 500 volts and can keep shocking for up to an hour. They also have a 10 volt system to sense ...
-1
votes
1answer
127 views

Generators and electric motors

In a diesel generator, instead of using diesel engine can we use an electric engine and connect the motor and generator to the battery? will this make it an infinitely moving system or will the ...
0
votes
1answer
49 views

Applying more current? [closed]

An electric motor draws 20 Amps, when at maximum load of x. Can that value of current be applied even if the load was ten times less than x from a certain power source?
4
votes
3answers
3k views

Why is electrical energy so difficult to store?

Does anyone know a general answer to these questions? (I've asked them together because they're all pretty related, it seems.) Why is it that we find electrical energy so difficult to store? Do we ...
1
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2answers
272 views

Explanation of NMOS processes

Gate (poly-Si + $SiO_2$) and $p^{-}$ silicon operate as capacitors. But how are voltages and charges applied? In order for inversion to occur, there should be charges formed in poly-Si, right? How ...
7
votes
2answers
158 views

Does a radio receiver add a load to the transmitter?

If I have a dynamo connected to a switch and a load (such as a light bulb), the load on the dynamo is increased when the switch is closed and the light comes on. The dynamo gets harder to turn. Is ...
0
votes
1answer
147 views

What is the difference between a battery and a “polarized” charged capacitor?

I know that the main difference between the two is that a battery can provide a constant voltage whereas a capacitor's voltage decreases as the charge stored decreases. But what about the internal ...
0
votes
1answer
125 views

Magnetic core, and a DC solenoid

A DC solenoid creates a magnetic field B. A highly permeability magnetic core is added to solenoid to increase B. Now, there is change in flux, due to the increase in magnetic field. What would be ...
1
vote
0answers
71 views

What does “although electrons enter and leave the diode, charge is carried by holes in the p-type region” mean? [closed]

I read this in an electronics book but I couldn't understand it: The flow of current through a forward-biased diode may be summarized like this. Electrons pass from the external circuit and ...
-5
votes
1answer
144 views

traditional transformer design improvement [closed]

The traditional tranformers suffer a lot of losses in various forms, some of them are as follows : 1. Flux leakage 2. Eddy currents 3. Hysteresis Figure : But as we are taught induction we come ...
0
votes
1answer
397 views

Conservation of energy and ohms law in a step up transformer

In an ideal step up transformer with a constant resistance attached to the secondary coil, how is energy conserved and ohms law followed at the same time? $$\frac{V_p}{V_s}=\frac{N_p}{N_s}=\frac ...