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0
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1answer
93 views

Back EMF & Current, how can we make the current $I$ stable?

Lets assume we have a wire that has $10V$ across and $1$ $Amp$ flowing, now if this conductor is introduced to a changing magnetic field, $-EMF$ is induced, can we control our voltage to increase it ...
1
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2answers
137 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 ...
12
votes
1answer
437 views

What is the probability of quantum tunneling occurring in this CPU?

You may have noticed over the last few years that Moore's law is no longer applying to the real world. This observation states that over the history of computing hardware, the number of transistors on ...
0
votes
1answer
107 views

Is the passive reference configuration different from the conventional direction of current?

Is the passive reference configuration different from the conventional direction of current? According to the passive reference configuration, current enters the positive polarity of voltage, while ...
2
votes
2answers
59 views

Why is the electric field highest in regions of highest resistance?

I know Kirchhoff's law and that current must be constant. But what exactly is the phenomenon, from first principles, that causes the electric field to be stronger in a region with lower carrier ...
0
votes
3answers
100 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 ...
0
votes
1answer
126 views

Does doping silicon affect its coefficient of thermal expansion (CTE)?

Everywhere I have searched I always see the CTE of silicon listed as 2.6*10e-6 °C^-1. However, I have silicon that was phosphorus-doped to an ion concentration of of 2.41*10e11 atmos/cm^3, and I would ...
7
votes
6answers
11k 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 ...
0
votes
4answers
176 views

Ohm's Law Question?

Since $V=IR$, if you were to have say a $5\:\mathrm{V}$ source connected directly to ground, no components in the circuit at all, you would need to add resistance for the current to flow? Or is there ...
2
votes
3answers
58 views

Does the equation CV = q break down when V is small or a wire is very long?

I'm trying to understand how the equation $CV=q$ relating the voltage difference and charge stored on a charged capacitor breaks down under extreme circumstances. In most problem statements that I'm ...
1
vote
0answers
25 views

Help with finding an equation to work out the length of cable required to produce loss of colour on an analogue video signal

When I briefly taught Broadcast Engineering I set up an experiment in order to demonstrate the effect of signal reflections along coaxial cable on an analogue PAL waveform. It involved getting the ...
9
votes
3answers
4k views

Is it viable or possible to make your own transistor?

Just wondering if it is possible/viable to construct your own transistor, not small like todays, but the same scale as the one created at Bell Labs.
0
votes
1answer
32 views

How long can a cellphone battery(pictured) power a LED light that produces light equivalent to traditional 60W bulb(800 lumens)?

Assuming Energy Star rated LEDs which produces 100 lumens/watts. Battery rated as 9.88Wh. Power consumption by LED = 800 lumens/100lumens/watt = 8 Watts Does it mean that it will power circuit for ...
6
votes
2answers
629 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 ...
0
votes
0answers
23 views

Would touching a bimetal probe short a nichrome wire heater?

Long story short: found electrical equipment box to play with. So would trying to get the temp of a heated nichrome wire with the use of a k probe short the nichrome? (k probe touching the wire) And ...
0
votes
0answers
32 views

Tunnel diode/quantum tunneling

How does a tunnel diode work?/How does a tunnel diode use quantum tunneling, and how does quantum tunneling make the diode faster?
1
vote
1answer
32 views

In a noiseless environment, how accurate do today's transmitters send EM waves?

Suppose that there is no external noise in the environment. How accurate are today's TEM wave transmitters in such a case? So if we want to send $200\cos(1000\pi t)$, can transmitters send exactly ...
0
votes
1answer
39 views

What is the difference in the behaviour of the commutator in a motor between DC and AC?

Is it correct to say that in DC, the split ring commutator produces direct current flow and therefore stronger voltage, as opposed to AC which produces alternating current and therefore weaker ...
-1
votes
1answer
63 views

What device is best to prevent electric motors from burning out? [closed]

Is there any equipment to prevent electric motors from burning out? I have researched about Transient voltage surge suppressor TVSS and also Surge protection device. Can this help?
1
vote
4answers
6k 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 ...
0
votes
1answer
30 views

There is some attempt to build a magnetic flywheel (reservoir of motion)

We know how flywheel works! There is some attempt to substitute the flywheel-friction mechanism for some magnetic torque ? Exist some mechanism that uses thermal cycle of gases for generate magnetic ...
1
vote
1answer
30 views

Stability of an unstable system using nonlinear element, is it possible or not?

Say there is a system with open-loop transfer function $$ G(s)=\frac{1}{(s-1)}$$. The system is definitely unstable. If I put any nonlinear system in cascade with $G(s)$ and from the output, a ...
0
votes
1answer
56 views

Can incandescent light bulb can be brighter if fixed power?

I found that luminous efficacy of 60 W tungsten incandescent bulb is 14.5 lm/W. Is this value defined by design details listed above or it depends on something else too? Can we design 60 W tungsten ...
0
votes
2answers
809 views

Explanation for transistor as amplifier

In transistor as an amplifier, we have NPN transistor (base in the middle and emitter and collector at the sides). The collector has electrons in majority because it is N-type. similarly, holes are in ...
0
votes
0answers
22 views

Holding a photolithography mask (EUV litography) with magnets, to minimize deformation on the photomask?

Some background: what is this question about? On 20/11/2014, I visited the ASML Holding in the Netherlands, which is according to them, and according to Wikipedia: the largest supplier in the ...
0
votes
0answers
19 views

Problem with the sign of the Thevenin resistance in a circuit

I have the following issue: when I want to find $R_{Th}$ for a circuit with dependent sources, I excite the circuit with a voltage Vo, and then proceed to find the resulting current $I_0$. Finally, ...
6
votes
1answer
877 views

How did the Bardeen-Brattain point-contact transistor work?

I've been trying to understand how the Bardeen-Brattain point-contact transistor worked. The point-contact transistor uses Schottky barriers (metal/semi-conductor junctions), so under what conditions ...
0
votes
1answer
67 views

Load resistance adding with minimized power and voltage constraint [closed]

Consider the simple circuit below: Suppose $V$ and $R$ have set voltage and resistance values respectively, and you are to choose the resistance values for $R_1$ and $R_2$. However, you must choose ...
3
votes
3answers
604 views

The role of resistor in e.g. an AND gate

What is the role of the resistor in e.g. an AND gate like this one? : One often sees lots of resistors in electric circuits, but I haven't really understood their role.
0
votes
1answer
3k views

Capacitance per unit area and CMOS case

In a modern 0.35μm CMOS processor, the gate oxide thickness is around 80Å = 8nm. This gives us a capacitance per unit area of $430nF/cm^2$ I am not getting how one gets this capacitance per unit ...
23
votes
5answers
2k views

Quantum random numbers from a laser — simplest setup?

I'm a software / maths guy who would like to build a physical setup for generating quantum random numbers. I have no physics background, so bear with me. Background The project is for a public ...
2
votes
2answers
98 views

Why a tunnel diode (TD) is called a diode?

Traditionally, a diode is a 2-terminal device that limits current to flow in one direction, i.e. a rectifier. But a "tunnel diode", according to wikipedia, is not rectifying: In the tunnel diode, ...
0
votes
2answers
42 views

Internal Combustion Engines

I need to know the typical energy balance of an IC engine and where this energy goes, but I am unsure what exactly they are asking? Engines are not my main strengths, so I could do with as much as ...
0
votes
1answer
23 views

Why does material change electrical property based on frequency of input electrical signal?

I was investigating whether dry soil would conduct electricity. What I found was that at 60 Hz frequency (i.e. power line fell to the ground), dry soil is a very good conductor. But if you increase ...
0
votes
0answers
310 views

Why do we apply Fleming's *left* hand rule in case of DC motors but use Fleming's *right* hand rule in case of generators?

Why do we apply Fleming's left hand rule in case of DC motors but use Fleming's right hand rule in case of generators to find the direction of induced current?
1
vote
0answers
42 views

Why didn't all three of my electrical fuses ignite? [closed]

I built a rocket that used 3 x solid fuel motors. To ignite them I used 3 electrical fuses, which are basically a thin filament of wire which heats up when given enough voltage. Only 2 of the 3 fuses ...
1
vote
3answers
116 views

How to use phasor method for analyzing electrical circuits when current has DC components

So let's say that we have a electrical circuit with a current source that is sinusoidal, but has DC offsets. How then do we convert this $i(t)$ into phasor $I$? Or is this generally impossible?
0
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0answers
14 views

How does time relate to frequency in terms of averaging to reduce noise?

It seems for the longer time we average, the more frequencies we can incorporate in calculating the V(rms) of the noise. Why is this?
0
votes
2answers
7k views

How does current flow from the emitter, through the base and to the collector in a NPN transistor?

So, I understand that for a NPN transistor to work the emitter-base junction needs to be forward biased and the collector-base junction needs to be reverse biased. I understand how current flows from ...
4
votes
0answers
117 views

Building a Faraday cage for mobile networks that is transparent for optical wavelenghts

A friend of mine is working on an architectonic project, where she designs a Faraday cage type of open space built in parks or other public places. The initial thought is to build it from some sort of ...
0
votes
1answer
522 views

Determining energy stored in capacitor and inductor in RLC circuit

I've been stuck on the following homework problem for a few hours now with little progress. As you can see, it's a relatively simple RLC circuit with a couple independent sources and a ...
-1
votes
1answer
73 views

how can we apply the formula p=VI in power transmission lines?

i mean we don't know the value of voltage across the power lines...we just know the potential at which it is generated which is not the potential difference across its ends..say electricity is ...
1
vote
0answers
46 views

What is DX technology and what are the effects on digital cameras?

I am photographing in a high power voltage field in Industry producing aluminium, called DX technology. How do I know if my digital camera will not be affected? At 350kA current my film cameras were ...
7
votes
5answers
7k 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 ...
0
votes
3answers
68 views

What stored charges do in a capacitor? [closed]

Why does a fan need capacitor? Capacitor is just providing charges to fan but it can be accomplished without it by directly connecting fan with electric supply. Which other appliances need capacitor?
2
votes
2answers
73 views

$ε_0$ affects electric field intensity, but $μ_0$ doesn't affect magnetic field intensity?

I'll be honest: this question is actually a homework problem. I've spent the past hour going through Google and several textbooks trying to answer the question "Why does $ϵ_0$ affect electric field ...
0
votes
1answer
201 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 ...
2
votes
0answers
173 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 ...
1
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0answers
24 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
vote
3answers
585 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 ...