Short Definition and 523 Threads

Hi guys, Kind of newbie in this forum, i would like to ask your opinion in the following issue. I have an application using one Generator (50Hz-400Volts) connected in parallel to the grid (50Hz-20kV) thru a step up transformer (Ynd, 0,4 to 20kV). I have performed a short circuit study for...

In Dummit and Foote, a short exact sequence of R-modules 0 \rightarrow A \rightarrow B \rightarrow C \rightarrow 0 (\psi:A \rightarrow B and \phi:B \rightarrow C) is said to split if there is an R-module complement to \psi(A) in B. The authors are not really clear on what the phrase "an R-module...

hi all, i want you to post best mind boggling/twisting questions you know of. Thanks dpa

Short problem, but why is this the answer? Confused :( Suppose \sum_{n=1}^\infty a_n converges. Determine the convergence of \sum_{n=1}^\infty a_n+4 The answer is "divergent," but I don't see why that's necessarily true. I would assume we wouldn't know whether a_n + 4 is convergent/divergent.

...at least, I assume that's what ESTOL stands for. Hoohah! A Hercules takes off with what looks like zero runway roll (at 1:07). http://www.youtube.com/watch?v=UxfpGPWtoOY#t=0m23s

A voltmeter must always be connected in parallel right? But when I have a transformer's secondary coil which is connected in series to it, then why is there a voltmeter reading? If i connect a battery in series with a voltmeter, the voltmeter reading will be the voltage of the battery right? So...

This is a theoretical question. Say we are imagining a way to detect whether a pair of circuits might be shorted together. There’s already hardware and firmware that sends pulses out on both of the circuits, and measures the response on the outputs. So, would we want to recommend additional...

Can a short circuit occur when a neutral wire is earthed, example a man touches a bare neural wire with bare hands..? And is the effect different for alternating and direct current?

What's the difference between short term memory and working memory? Is there any physiological difference?like difference in neural network formation? Thx!

Hey all, Between two devices, I will need to have a coaxial line (with SMA connections on either end) connecting them. The operating frequency of the signal I am propagating is approximately 125 MHz. With this said, the wavelength (assuming ideal) is 2.4 meters. I have heard from numerous...

Homework Statement Calculate the following expressions: Homework Equations The Attempt at a Solution Letting the vector a = (a_1, a_2, a_3) I've worked out that it's 2|a|^2 While that method is fairly quick, I don't particularly like it, and was wondering if there is a shorter or neater...

Homework Statement Consider the following intervals: A = [-3,5), B = (3,8), C = (0,4] Find: A\capB and A\capC The Attempt at a Solution I thought that: A\capB=(3,5) and that A\capC=[0,4] as that is the intersection point, but this book (Schaum's Probability Outlines) says that A\capB=[-3,8)...

Please tell me if there are mistakes, however small, in the answers I have provided to these questions. Thank you in advance. 1. Why are pulsars not always associated with supernova remnants? Most pulsars are created by Type II supernovae, but out of all the pulsars detected yet (around...

Hi I know that for a short solenoid (L<R) the magnetic field at the axis is (standard EM) B(z) = \frac{1}{2}\mu_0 \frac{N}{L}I(\frac{z+\frac{L}{2}}{\sqrt{(z+L/2)^2+R^2}} - \frac{z-\frac{L}{2}}{\sqrt{(z-L/2)^2+R^2}}) where R is the radius of the solenoid, N the number of turns along the axis...

I have a circuit which i designed to have gain around 60dB unfortunately when I tried it out the circuit's gain falls short around 30 dB. and also when i tried it out with electrode, the circuit's gain got lower than 25 dB. My problem is what are the reasons that cause this problem and if I...

Homework Statement This is more of a concept question rather than a HW problem, but I have two Circuits shown in the image attached. I am not really understanding how a short would affect resistance in these cases. 2. The attempt at a solution For figure 1 I am considering one of two...

In my phototelectrochemical setup I have a working electrode, reference electrode and a counter electrode . Now I need to measure the short circuit photocurrent so that I can calculate IPCE (incident photon to photocurrent efficiency). How will I measure this current ?

Here are a few: http://codecogs.com/latex/eqneditor.php (WYSIWYG) http://tobi.oetiker.ch/lshort/lshort.pdf (PDF) ftp://ftp.ams.org/ams/doc/amsmath/short-math-guide.pdf (FTP)

Homework Statement Find the current flowing through the voltage source in mA. Assume Vs = 3.9 V and R = 8.3 kohm. Round off your answer to two decimal points. Homework Equations 1/R(equivalent) = 1/R1 + 1/R2 + ... I=V/R Kirchoff's voltage law The Attempt at a Solution I considered the 3...

The Question The Planet V has a year lasting 360 days. In the same star system is the Planet X. The Planet X has half the mass and triple the radius. A planet X year would be approximately _____ days The attempt at a solution Givens: Tv= 360days Tx= ? mv = mv mx = 1/2mv rv = rv rx = 3rvI...

An electron and a proton can not form a neutron because they are short about 800KeV of energy. If we place an electron 200 fermi from a proton there is a strong electrostatic attraction. As the electron moves towards the proton electrostatic potential energy is converted to kinetic energy of the...

Can someone explain what short circuit duty is? I see this a lot in my field but I don't know what it means. I see it in the context of new generation coming onto the grid and needing to interconnect to the current transmission system.

The only evidence I have is from introspection, but it's happened so often I'm wondering if it's a more common experience. The day after drinking heavily my mind is not sluggish. It's lightning fast. I'm extremely sharp, I talk very quickly, produce more jokes, see though irrational...

And now for the long story. I'm a first time poster, long time reader. A little bit about me, I am in my third year of undergrad studying way too many subjects yet not studying at all. I have jumped from philosophy, to physics, to bio, to economics, and now math. During this time...

Homework Statement Homework Equations Usual equations for calculating Fourier series coefficients The Attempt at a Solution Well essentially I don't know what to let f(x) equal to for calculating the coefficients a0, an and bn. Should I use 1 + x/pi or 1 - x/pi? And what about...

I need to write a MIPS program (using only 2 true-ops) to take in 1 signed integer argument into register $a0, and return (into $v0) a 1 if the input was negative, and a 0 (into $v0) otherwise. Can anyone offer help. I'm not sure since I can only use 2 instructions.

I'm writing an essay for a contest and I'm about half way done. I want to know how accurate my information is. It should be self explanatory as we are supposed to write it for the general non-physics person who might have no clue about the subject. The asterisks are places where I'll have to...

My book says, initially, an uncharged capacitor acts as a short circuit and we eliminate any resistors in parallel with the capacitor. My question is, how can a capacitor be a short circuit if there is a gap between them? How does current go through a capacitor initially?

I just want to be up front with all of you, I am not a physics guy. I am trying to accomplish a goal. I need to focus a two inch electromagnet's energy into a quarter inch diameter area, four inches away from the magnet. Can this be done and how? Please explain in laymens terms, drawings would...

when the oil price increase which will have high impact either long haul aircraft or short haul. I mean which kind of aircraft keeps the airliner profitable. Though the increase in oil price will have an impact on both kind of aircraft.

Homework Statement Here is the problem: http://img507.imageshack.us/img507/6488/unled2b.jpg What is the open circuit output voltage, Vout? Estimate the short circuit output current Can someone explain to me how to do these. Homework Equations Honestly... no idea. I know V=IR and all that...

I apologize if the breadth of this question requires a response beyond what anyone is willing to contribute. I've started researching optics ( of which I have little knowledge ) and feel immediately overwhelmed. Problem Using a DSLR ( with a DX size sensor ) and preferably the available lens...

I don't know what's wrong with it. My antivirus doesn't detect anything and I built the think in February. It's Windows 7. It just started about a month ago but it does it occasionally and it has me worried. What could it be? When it freezes, I can still move the mouse around but it won't...

http://en.wikipedia.org/wiki/Square-integrable_function According to the tutorial: it says g*(x) is the complex conjugate of g but I can't get the idea from where this g(x) function comes, than why is it the complex conjugate? And it seems i can't visualize the inner product space...

Today our physics teacher teach us how to find resistance of a network of resistance that is messed to heavily(example all sides of a cube are resistance find resistance). Ok those are very good methods, but it seems that they are not result of experiments done by genius persons it seems that...

I'm studying for a quantum exam and there is this symbol that looks like an inverted plus minus but the minus is attached to the plus... kind of like _ + but attached. in context: "x ± vt = constant or x = (-/+) + constant." Thanks for any speedy help!

Homework Statement Suppose A = {1,{1},{1,{1}}} Then is {{{1}}} an element of A? The Attempt at a Solution I am thinking A has the elements are only 1, {1}, {1, {1}} But {{{1}}} has only the element {{1}} While A has the element {1,{1}}, you can't just take out the...

Homework Statement My computer crashed, so I can't check my code I wrote, and the school linux lab is full, so I really need some help. I already wrote the code (ill post it below) so I can't compile it and check for some errors. Can anyone quickly glance it over and see any mistakes...

Hi guys, After doing some reading on transformers and reading solved examples there was one thing I couldn't quite figure out. There was a transformer with all the nominal data (10k/0.4k kV/kV, 100kVA), it said that they made a transformer short circuit test when one side is shortened and...

I would like to use a timer to turn on and off a 220 Volt appliance. With a "mechanical" plug-in timer you have 20 minute granularity. But I would like to have a 1 minute resolution. For example - 1 minute off and 1 minute on. I bought a cheap 10 euro digital timer. I was mislead by the...

Homework Statement So the first part is to find Voc in this circuit: So I did this: -10 + 1200*i1 + 3300*(i1 - i2) - 12 = 0 since i2 = 0 A, -22 + 4500*i1 = 0 i1 = 22/4500 A = 0.0049 A Then, for Voc: 3300*(i2 - i1) + Voc + 12 = 0 since i2 = 0 A, 3300*(−22/4500) + Voc + 12 = 0...

Homework Statement Homework Equations Thevenin Theorem, Kirchoff's Voltage Law, mesh analysis The Attempt at a Solution I'm kind of confused as to how to approach this question as a whole because I'm getting put off from the two voltage sources. I was thinking that maybe I could use mesh...

How do i find if there is a short circuit in the circuit diagrams. i am really confused. please help.

I was taking a lecture series this summer at my school where a professor was introducing us to introductory Galois theory. It was a very 'slack' introduction, without too much rigour. However, about a month in (only 3-4, 3 hr lectures) they stopped due to outstanding circumstances. I was a...

Hello guys, I am totally new to EE and in need of info on a project I am working on. I am trying to broadcast a short range signal and the distance the signal can travel needs to be limited. So let's say I want the signal to reach up to 600ft. I need it not to be easily received by other...

I only have my period for 3-5 days every month, and I haven't been on any hormonal birth control for almost 3 years. I had been on the pill for a few months (in the past), and the Nuva Ring for about a year (the last BC I used). I have also spent nearly a year using the pull-out method. (I know...

Saw a calculation of stress in a datasheet (page14) here - http://tinyurl.com/43465sv (The device drives a Mosfet.) How do you relate the P^2 t stress calculation in the datasheet to the Safe operating area curve in a Mosfet datasheet. If the Stress is 20W^2 sec, then how do you...

Hello all! During mitosis the telomeres reduced. But neurons do not divide during postnatal period (neural stem cells are exclusion). So - does Hayflick limit exist for neurons? Thanks

I've been enormously impressed with the core members of this forum, especially hurkyl. There was a guy who claimed to have a proof of FLT, and hurkyl and others gave him a lot of time over two weeks and were much more fair to him than he deserved. Since I'm hoping to get a fair hearing for my...

For personal purposes, I'm trying to summarize the last 14 billion years. How accurate is the following? Any thoughts welcome, thanks! Most scientists believe the universe is at least 14 billion years old based on evidence about the relative movement and expansion of galaxies and other...