Short Definition and 505 Threads

our aim is apply the principle of induction heating in the transformer by short circuiting the secondary of the transformer... the heat produced from it should produce large amount of heat ... if u have any idea pls reply me... also suggest tha rating of the transformers and other instrument

Homework Statement An underground telephone cable, consisting of a pair of wires, has suffered a short somewhere along its length (at point P in the Figure). The telephone cable is 6.00 km long, and in order to determine where the short is, a techician first measures the resistance between...

Hello All, Am studying GR using a text by Hartle. From time to time need a better intuitive understanding of hyperbolic functions than I currently have. Never learned them for my physics undergrad. Any short sweet highly understandable primer, etc, that anyone knows of (preferably free of...

I’m in a situation where I need to power 150 machines, each one consuming 2kW of power. The trick is that it rolls on a metal track at high velocities. I am concerned about transmission loss and type of contact. I could power the machine with a physical contact via carbon bushings to a...

Hi Everyone, I hope everyone had a very enjoyable holiday season. Currently I'm developing a short film to shoot later this year. Being ever fascinated with the natural universe and also theoretical physics this film will be a welcome new approach to the science fiction genre. The goal is...

Hello! The incompressible Navier Stokes equation consists of the two equations and Why can't i insert the 2nd one into the first one so that the advection term drops out?! \nabla\cdotv = v\cdot\nabla = 0 => (v\cdot\nabla)\cdotv = 0

Given a finite group G is G isomorphic to the Galois group of some polynomial in Q? Having done a course on Galois theory I think I just missed this and I feel like I ought to know the answer. Did I just sleep through that part of class? :/

please read all the question and when answering only some, mention which question you are answering 1. matter is a "frozen" energy (yes or no) 2. heat is energy, measured by the movement speed of molecules 3. electromagnetic waves as the go next to the to the atomes they pull and push the...

I understand that liquid water cannot exists on Mars for extended periods of time because: a) The atmosphere is too thin b) Resulting in a lower boiling point water c) Which leads to sublimification of solid ice into gaseous vapour Quite specifically, I would like to understand the...

Hello I am trying to speed up a code which performs a number of tasks on a set of data. I am wondering if there are any resources on general rules and principles that can be used to speed up calculation times? I am having a real problem when there appear to be more than one way to code...

hey, I think its time to ask a expert on the matter now. I apoly for my bad English writing at first, I'm from Denmark 26 year old We all know you can take a straw and put it into a glass of water and put your finger at the hole in the other end and pull some of the water up with the straw...

Homework Statement You drill a hole at the end of a solid thin rod of length 1.3 m, and then attach the rod through this hole onto an approximately frictionless pivot. You then release the rod from rest at a reasonably small angle from vertical, so that it executes simple harmonic motion...

I want to say that f(x) = |1/x| is in L-infinity(E) when m(E)<infinity becuase the function has and esssup on any measurable set, E. Even if E = (-1, 1) f(0) is not a problem since it is only one point... But wait... what *is* the esssup for this function on (-1, 1)? I think it might not have...

Homework Statement I have several problems in which I am to solve for all variables in a series circuit. Then I am given a follow-up question in which a resistor, or multiple resistors, short out or open. I am then required to calculate the variables in the altered circuit. Homework...

1. A defensive lineman breaks through the line and flattens the quarterback. The magnitude of the force he imparts on the poor quarterback is (a) greater than (b) the same as (c) less than, the magnitude of the force the quarterback imparts on the defensive lineman. 2. Not sure of any 3. I...

rotating disk short question! Homework Statement If object is rotating on a disk with a constant angular speed, which of the following is zero? the object's tangential acceleration the object's centripetal acceleration both (a) and (b) are zero niether (a) or (b) are zero...

-My professor said that if i is constant through an inductor that V=0 through the formula V=L(dv/dt) . So if an inductor is in series with a voltage source it will act like a short circuit. But if the inductor is in series with a resistor and the voltage source the inductor will not act like a...

I read in the Feynman Lectures, section 5-8 in Volume 2, that Coulomb's law may begin to break down at distance scales shorter than 10^-14 cm. Feynman says that, at the time of his lecture, the question was still open. Does anyone have any new information on this question? Thanks, Djinn

Homework Statement An underground telephone cable, consisting of a pair of wires, has suffered a short somewhere along its length (at point P in the Figure). The telephone cable is 4.00 km long, and in order to determine where the short is, a technician first measures the resistance between...

Hey all, I am just wondering if one can directly calculate the Einstein coefficient in spontaneous emission of, say, two-level atoms through feynman diagrams? I searched for sources in google but could not find anything. Thanks a lot for an answer! Wit best regards, blue2script

I just have a quick question. Which way of Atom Excitation is more efficient? Photon Energy which matches the absorption peak(s)? Or Photon energy of a Shoter wavelength than the absorbtion Peak?

short wavelengths carry no energy? Hey guys (and girls), I'm reading the book "The Black hole war", by Leonard Susskind and on the page 208 it has written something that kind of surprised me. I ll just quote an entire paragraph: "The hypothesis that light is composed of indivisible photos...

How does this annihilation process play in semiconductors? Initially i thought that as long as the an electron gets enough energy to move into conduction band (in an energy diagram) - it will move and wander within the Conduction band. However, i have a slide notes about annihilation that talks...

Hi, Is there any method by which problems involve short exact sequences can be solved. For example, if I have : 0->Z->A->Z_4->0 how can I decide what is the middle group without knowing any of the maps Thanks! S.

Hi guys, I'm looking to find out if there is a ratio between short term and continuous current for power cables. I know that people usually generalize around 5-10 x rated ampacity, but I'm just asking around to see if there is a certain #. On McMaster Carr, the highest rated cable is for...

"cutting" movies short One of the things I enjoy after seeing a god awful movie is looking up the reviews for the movies. I notice in a lot of the movies, that a typical excuse for a bad movie is that the film was cut short by the company producing the film. Now, does this mean the film was...

I want to make short term investments (currently, stocks I believe). Currently, I don't have any investment knowledge so wanted to know if stocks are better or forex? (edit: learning about them in next few days) I found this website: http://individuals.interactivebrokers.com/en/main.php If...

I have a 24 KW 3 phase 120/208 volt synchronous generator I bought from China and I am having trouble finding the available short circuit amps or the %Z rating. Is there a chart anyone is aware of for common short circuit capacities?

Hey! A friend of mine is short sighted. She told me that when she looks in a mirror, objects that are reflected from a distance appear blurred in exactly the same way they do as when she looks at them directly (from the same distance). She also told me that objects that are near but small are...

A question for the more theoretically oriented forum users... but please feel free to suggest an answer to the puzzle anyways. In the book of selected works by Glimm & Jaffe, on page 4 (they discuss the massive scalar interacting filed in 1+1 dimension and give an overview of the divergences...

hallo, what is the reason for sparks once i have a high voltage short circuit? Thanks, Omri

Hello, I am working on building a wireless power system, I have looked into it a bit and the best if not only way seems to be a resonant air core transformer. My primary coil/circuitry can really be infinite in dimension, but my secondary coil needs to be no more than 2 inches in...

Homework Statement i) Explain why in alpha decay short half lives correspond to large disintegration energies. ii) Determine the energy release during the alpha decay of 238U to 234Th. The mass of 238U is 238.0508mu, the mass of 234Th is 234.0436mu, and the mass of 4He is 4.0026mu...

so, I'm pretty bored and decided that i want to make a speaker. I've bought some thick copper wire, and twisted it in the form of a coil, then twisted some more with a larger radius so i can put the first one inside the second one and so on.. my motivation to buy the thick wire was to maximize...

Homework Statement A particle initially moving at 5m/s has an acceleration of a=-.5v. Find v(t) Homework Equations The Attempt at a Solution i know the anti derivative of acceleration is -(v^2)/4 but i have no idea how to put velocity in terms of time when acceleration in terms...

I have completed an experiment to measure the decay rate of an isotope, and I am trying to estimate uncertainties. The half life is 40 seconds, with decays counted over a 15 second period (with many of these 10 second periods for a total of 6 minutes of recordings) However in more detailed...

Homework Statement A 110 g arrow is shot vertically from a bow whose effective spring constant is 500 N/m If the bow is drawn 55 cm before shooting the arrow, to what height does the arrow rise? Homework Equations F=ma U=kx^2 - for Spring (bow) F=-kx KE=1/2 mv^2 W=fs The Attempt at a...

Hi everyone! I would like to solve some questions: Classify up to isomorphism the four-sheeted normal coverings of a wedge of circles. describe them. i tried to to this and it is my understanding that such four sheeted normal coverings have four vertices and there are loops at each of...

Abstract algebra question. Given the short exact sequence $ 1 \longrightarrow N \longrightarrow^{\phi} G \longrightarrow^{\psi} H \longrightarrow 1 $ I need to show that given a mapping $ j: H \longrightarrow G, and $ \psi \circ j = Id_h $ (the identity on H), then $ G \cong N \times H. (The...

1. Invariants in field strength The first part of the question asked you to calculate the Lorentz scalars by contracting the field strength tensor (F) and it's dual (G): FF, GG and FG (index's omitted) and formed ±2(B²-E²/c²) and -4/c(E.B). The next part asked: Are there any other...

Homework Statement 2) 2 resistors, 42 and 64 ohms, are connected in parallel. The current through the 64 resistor is 3A. Determine the current in the other esistor and what is the total power supplied by the two resistors? Homework Equations The Attempt at a Solution 2) How...

1. Platinum is silver and shiny. Why? 2. Aluminum oxide can be either transparent, red or blue. How? 3. Quartz is transparent. Why?

Homework Statement 1) When a swimmer dives into water just before piercing himself into water, he stretches himself. Why? 2)In a tug of war if the parties on both ends of the rope apply apply equal and opposite forces on each other then how can one party win? The Attempt at a Solution...

The problem is that a space heater develops a short circuit when to much current enters the circuit. The power supplied is 1500 W and the max current before short circuit is 15A. Firstly we have to calculate the resistance of the heater where I used P = I^2 R. But now we have to find the...

Homework Statement Solve the equation log x4 - log x3 = log 3x - log 2x I know the laws of logs and I cleared all the other log questions in seconds but I can't figure this one out Homework Equations I know that log x4 - log x3 is the same as log x4/x3 but what I was wondering is if...

Thanks again for the comments on my previous post. I've done some work narrowing the field of math schools. Note that since my previous post I've made a decision to weight schools in the south a bit more heavily than those in the north. Here is a list, along with my comments. AMS Group I...

hi, I have this problem I've been stuck with for a long time and i can't figure out what to do. if spherical coordinates are denoted (r,θ,ϕ) and cylindrical coordinates are denoted (ρ,ϕ,z), how do i express the radial unit vector in cylindrical coordinates, e(ρ), in terms of the spherical...

Homework Statement A copper bar is moved to the right while its axis is maintained in a direction perpendicular to a magnetic field as shown in Figure P31.28d (image d, bottom right). If the top of the bar becomes positive relative to the bottom, what is the direction of the magnetic field...

Is parkour suitable for tall men to practice? Will it add larger probability to tall men to get hurt considering taller men has lower bearing surface to body mass ratio?

Hi, I'm trying to perform a short circuit fault calculation on this transformer and load I have when a 3 phase bolted short (worse case) occurs. The transformer specs are below: Z(transformer)=5%, Z(cable)= .00306 + j.0027, Delta/Star 6.6kV/400V I can understand calculating the short circuit...