Generation Definition and 363 Threads

So from the first law for a closed system, dU=dQ-dW=dQ-PdV From the second law, dS=dQ/T + Sgenerated (i.e. the entropy generated) Putting expression of dQ from second law into first law, dU=T*dS-T*Sgen-PdV If s and v are constant, dU= -T*Sgen>0 Hence dU<0 This is a...

Dose anyone know that what is the newest generation of solar cells?

I am sure this is a set of naieve question first of all. However i'd appreciate someone taking the time to enlighten me, as my mind is boggled by this and has been for some days now. I have watched numerous videos on the subject of electricity but am still somewhat confused. My issue is taking...

I've got a couple of questions about reversible cycles: So if we have two gaseous systems and have a reversible cycle working between them, then the entropy generation within each gaseous system is zero, right? Do turbines execute reversible cycles? Thanks a lot for your help!

Hi all, I've been doing some pretty complex problems on closed systems in thermodynamics, and a few questions pooped up in my mind about Sgen (entropy generation). Please help me out with them.. 1. When work is done on a system (like a paddle wheel in a cylinder containing gas), there is...

If you are a fresh graduate of BSc Electrical Engineering and you are asked to choose either Transmission & Distribution Department or Power Generation Department, which one will you choose? And why? Please your inputs will help me decide, so help me out. Airer

This was just posted today, and looks interesting http://arxiv.org/pdf/1309.1137.pdf A New Generation of Atomic Clocks: Accuracy and Stability at the 10-18 Level B. J. Bloom et al The exquisite control exhibited over quantum states of individual particles has revolutionized the field of...

In Dummit and Foote Chapter 15 on page 657 we find the following definition of a k-algebra: Let k be a field. A ring R is a k-algebra if k is contained in the centre of R and the identity of k is the identity of R. This defintion is followed by the definition of a finitely generated k-algebra...

On page 351 Dummit and Foote make the following statement: "It is easy to see using the Submodules' Criterion that for any subset A of M, RA is indeed a submodule of M and is the smallest submodule of M which contains A ... " I am not sure how to (formally and explicitly) prove this...

Hello, so today i was thinking about alternative ways to provide electricity to a motor in a fixed wing aircraft. Ideas: 1. Use thermoelectrics. They would generate the most voltage around the engine, so maybe they would only be placed here, or all over the aircraft. Advantage: unlike solar...

It is known that heat pumps create more energy than it consumes due to moving "heat" from one place to another. For example, if an air conditioner consumes 100 watts, the compressor will release 120 watts of heat since the heat in the room will be transferred to the compressor. Would it then...

Hi, I volunteer for a small group who try and help the families who live in the rural parts of Sri-Lanka We have built and donated a large number of solar powered lanterns but during the rainy season (or even on cloudy days) we don't get enough sunshine for the lights to work for their...

Hello, I was looking into some drawings for electric generation plant, and i figured out a high voltage transformer 13.6kv/380KV 600MVA that connects the plant to distribution line. My question is why they use only one transformer 600MVA? Why they don't use 3 transformers 200MVA each so in...

I've read that the reason why the academic job market is so swamped for Physics is because of the massive spending around Sputnik's launch which resulted in the hiring of tons of physics faculty, followed by anti-age discrimination legislation which allowed those Sputnik-era professors to stay...

Self explanatory title

I was reading an article in Time magazine in the waiting room of an allergy clinic today when I stumbled upon this article outlining the challenges and advantages of the main generations of the 20th century. I.e, greatest generation (WW2), Baby Boomers (Hendrix) X-gen(me and Molly Ringwald)...

An electric current going through a wire generates a magnetic field as per the right hand rule. Will a pencil stream of electrons traveling in a vacuum at near light speed also generate a magnetic field--??----Also, what would a hypothetical observer traveling at the same speed and direction as...

For the following question, the solution manual sets du/dt (change of internal energy) = 0. Moreover, it also set the change of total entropy to zero. Why is that? An electric motor under steady load draws 9.7 amperes at 110 volts; it delivers 0.93 kW of mechanical energy. The temperature of...

I find it surprising that China has found a way to measure intelligence! Let's kill all diversity and raise a new generation that are good at taking IQ tests.

Homework Statement Suppose an individual born at time $t$ maximizes life-time utility \begin{equation*} \max \ln(c_{1,t}) + \frac{1}{1+\rho}\ln(c_{2,t+1}), \; \rho>0 \end{equation*} subject to the budget constraints in periods t and t+1, respectively \begin{eqnarray} c_{1,t} +...

I watched a documentary recently about electricity generation, and I've been trying to figure out whether an example they provided is actually possible or not in theory. If a big wheel, much like a Ferris wheel, spins but slowly, very slowly (let's say 5 revolutions per minute), and you...

Hello all, Considering that Einstein told us that E=mc2, that means that any energy is generated at a cost of mass loss? to be more specific: When a power plant generates energy by burning gas or coal, a part of the particles in the fuel burned simply disappear and can't be found in the...

I understand that for a fixed massflow the minimum amount of power required to generate a thrust is: P = Massflow * ∫v dv = massflow *0.5* [v2^2 - v1^2] However, is it possible to produce the same thrust with less power using the Lorentz force in an electromagnetic accelerator? If so, how can...

Here is the abstract: http://pubs.acs.org/doi/abs/10.1021/nl304680w I would need to pay the $35 so I have not read the full text. Question: it says "...without Light, Heat, or Electricity." Where is the energy required to split the water molecules coming from? Jeff

Hi, it has recently occurred to me that current technology does not allow massive electricity storage, and this has made me rather confused, as this implies that power generation has to be exactly matching the demand of power at any given time or else energy is wasted because of generating too...

Hi, Do particles arise from perturbations in fields? Thanks,

Understanding conservation of energy during generation of entanglement. In the experiment for generation of entangled pair of photons via SPDC Single photons are struck on a BBO crystal. In about 1 in a trillion of such collisions, two photons emerge. Questions: 1. Is the...

Hi PF, I used the circuit shown in datasheet of AD633 to generate AM waves. But the output I got was not correct. I want to why this error comes and explanations will be helpful. I will have to go for BF194 designs else. Here in our labs transistor circuits seldom works. Why I don't...

Hello all, I had a question about Electromagnetic waves. Although it isn’t homework (just to settle something in my own mind) I thought this would be the best place to put it. Perhaps it would be best if I could explain a situation I could understand and then hopefully someone could bridge...

Homework Statement Imagine that all the electricity used in an average home comes from hydroelectric generation. Your task is to estimate the annual average rate at which water would need to flow to generate the power for that home (gallons per minute or cubic meters per second). Make your...

Homework Statement Consider energy generation in the Sun. Fusion through the pp cycle takes place within its core which has r = 0.2 Rs T = 1.3 x 10 ^ 7 K rho (density) = 1.1 x 10 ^ 5 kg m^-3 X (total mass fraction of hydrogen) = 0.34 The nuclear energy generation rate for the pp...

What are generations of particles and how are they organized into the different groups. What similarities do two particles in the same generation share?

In a heat transfer with internal heat generation what does the term "internal heat generation" mean? Is that applicable only if a body itself produces some heat (Like current carrying wires,nuclear fuel rods etc) Or if i have a two cylinders one within another,and if inner cylinder is heated...

Does the back emf in a dc motor start to appear after a slight delay(say 1 or 2 seconds) after starting up the motor? I have had this simple doubt for a long time.According to the "generator principle" both applied emf and back emf will always exist simultaneously.Also it would be in violation...

I am trying to figure out how I would go about finding the steady-state temperature distribution in an absorbing medium using the steady-state heat conduction equation: (1) -\nabla\cdot\left(K\nabla T\right) = q_{gen} where T is the material's temperature, K is the material's thermal...

Maybe someone here will have an idea where I can get some information. I am planning on making liquid nitrogen from air and will need to regenerate waste gas. This gas will be very cold (-300F) and will get transported through some tubing system. Is anyone aware of any plastic tubing material...

Please don't be harsh on me. I just heard of reversible equation and had this thought: Is it possible to separate reactants from equilibrium and then later use it for energy generation? Kind of like water evaporating and absorbing heat energy.

Hi, Can I get some learning material or guidance on how to build equipment for generating specific waveforms of DO-160 section 22? Thanks

http://img404.imageshack.us/img404/9523/dynamos.jpg I understand that when the rotating magnet spins, current should be induced in the coils which powers the lights. So what is the point of the soft iron core? The rotating magnet should magnetise it because it is near it, and it should...

Hi, Have a problem: I'm generating 2 lists in Mathematica: In: time = Table[(r - 1.0)/10.0 , {r, 10}] Out: {0., 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9} In: noise = Table[RandomVariate[NormalDistribution[0, 1.4], 10]] Out: {2.16764, -1.38203, -0.395928, -0.58616...

I know that things moving closer to the speed of light will decay at slower rates, but does this include the decay of third generation quarks into second and then first generation quarks? If a third generation quark is created and in an area of the universe where things are moving extremely...

Hello, I'm a first generation student, and I'm attending college for the first time. I created a course map by semester. I would like to get some input from you guys regarding its arrangement. Fall 2012 ENC 1101 Freshman Composition Skills I SPC 2608 Effective Speaking HUM 1020...

All the pieces are falling into place rapidly for the development a new generation of computers that only vaguely resemble the ones we have today. The single biggest innovation to look forward to in next generation computer hardware is what I like to call Frankenstein chips. Just as shrinking...

I'm wondering if there is a generally accepted mechanism by which a plume is formed and how this then applies to the Earth's mantle, and so-called "mantle plumes". Specifically I am a bit stuck on these questions: Do plumes require a thermal boundary layer as their source? What process...

OK, I'm designing an Open Source Kite Ring Generator. See kitepowercoop.org for details. I have designed a system which uses a large inflated torus with kites attached radially around the axis on which it spins. I believe that removing the inside hub of a standard wind turbine by working in...

Concerning this paper: Stimulated generation of superluminal light pulses via four-wave mixing. I have two questions: 1) How can we check that information cannot be propagated faster than light with this system? 2) What is the meaning of the last sentense of this paper: Thanks

I really want to do research in battery after I finish my undergraduate engineering course. which engineering course should I choose so that I am well prepared to do research in battery? (mechanical engineering, electrical engineering, chemical engineering) Thank you.

Top 3 facts that would blow the facebook generation away? Hi guys, i come on here and read every thread and try to undertand some of it. most of it blows my mind! so how about a top 3 facts that'l blow the public away. tx for your time if you participate i am in awe tx

from zero to infinity, and the first raw moment about zero is the first derivative of the mgf evaluated at t=0... then why do we need to integrate the function ? Wouldn't the first raw moment just be e^tx.fx(x) dx, i.e the derivative of the function we just integrated ? Why do we...

What's a good year to mark when the Internet Generation of Scientists will dominate sicentific activity? I define the Internet Generation to be a generation who has used the resources of the internet (such as physicsforums, of course) throughout all their scientific training, from elementary...