What is Power: Definition and 999 Discussions

A power outage (also called a power cut, a power out, a power blackout, a power failure, a power loss, or a blackout) is the loss of the electrical power network supply to an end user.There are many causes of power failures in an electricity network. Examples of these causes include faults at power stations, damage to electric transmission lines, substations or other parts of the distribution system, a short circuit, cascading failure, fuse or circuit breaker operation.
Power failures are particularly critical at sites where the environment and public safety are at risk. Institutions such as hospitals, sewage treatment plants, and mines will usually have backup power sources such as standby generators, which will automatically start up when electrical power is lost. Other critical systems, such as telecommunication, are also required to have emergency power. The battery room of a telephone exchange usually has arrays of lead–acid batteries for backup and also a socket for connecting a generator during extended periods of outage.

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  1. N

    Calculate the power measured by the detector at distance h from the source

    Homework Statement An isotropic point source radiates electromagnetic energy, and its output is measured by a thin disc-like detector of radius R. Calculate the power measured by the detector at distance h from the source, assuming that the plane of the disc is orthogonal to the line of sight...
  2. A

    Power output of a intercooler and turbocharger

    Homework Statement The power output of an automobile engine is directly proportional to the mass of air that can be forced into the volume of the engine’s cylinders to react chemically with gasoline. Many cars (like a 2008 Mini Cooper S) have a turbocharger, which compresses the air before it...
  3. wirefree

    Can a microwave VSWR meter be used to measure Power?

    G'day. Recently we conducted an experiment in the microwave engineering lab where we were tasked to measure power in, what's called, a Directional Coupler. Here you'll find much on it. My concern with the setup is that we took our measurements on a VSWR meter by noting off the db scale. So...
  4. Adrian Tudini

    Power of a Quantum Cascade laser by theory

    hi Just a little question. How does one calculate the power of a QCL by theory? Is there any free software that allows one to calculate the power of a inputted laser medium for a qcl? Thanks. Adrian
  5. T

    What is the torque exerted by the flywheel on the machine?

    Homework Statement Flywheels are large, massive wheels used to store energy. They can be spun up slowly, then the wheel's energy can be released quickly to accomplish a task that demands high power. An industrial flywheel has a 2.0 m diameter and a mass of 260 kg . Its maximum angular velocity...
  6. Y

    MHB Power Series (Which test can i use to determine divergence at the end points)

    Hello, I was given f(-4x)= 1/(1+4x), and I used the geometric series to find the power series representation of this function. I then took the limit of (-4x)^k by using ratio test. The answer is abs. value of x. So -1/4<x<1/4 I then plugged in those end points to the series going from k=0 to...
  7. N

    1st Order Differential Equation - Power Series Method

    Homework Statement The Attempt at a Solution I have deliberately made several obvious steps, because I keep ending up here. However I have no idea what to do from here. I thought about the fact, that differential equations have the solution ##x = x_{HOM} + x_{Inhom}##, but the ##x_{HOM}##...
  8. S

    Electric current flowing in a power transmission line

    A cable of resistance 12 Ohm carries electric power from a generator producing 250 kilowatt at 10,000 volts. Calculate the current in the cable. Solution using P=VI I=25A but using P=I^2R 250000=I^2×12 I =500/root 12 Amps What is the reason for the different...
  9. Celso

    Power waste (conceptual doubt)

    I'm currently in a undergrad level course of eletromagnetism and my professor found it useful to remember quickly of some relationships that we see in high scool, among them power waste. I got the formulas, since they're simple and are direct derivated from the definitions of electric current...
  10. P

    How to calculate my motor input power

    Hello, I have a question about calculating input power. Does the following formula work? Shaft Power (Supply) / Motor Efficiency? We are trying to calculate what an existing fan is using but do not have assess to site. We have the shaft power and motor efficiency from the manufacturers data...
  11. T

    How is the horizon length related to the power law spectrum

    Homework Statement For a power spectrum density fluctuations ##P(k) \propto k^n##, I need to find the scaling (with respect to ##a##) of the horizon wavenumber ##\frac{2\pi}{\chi_H}## in a matter dominated universe in terms of ##n##. ##\chi_H(a)## is the evolving particle horizon, in a flat...
  12. F

    Bremstrahlung Braking radiation spectra expected and total power

    as homework, I have to do the following exercise: Bremstrahlung emission : We are interested in ionized plasma of density ##n##, at temperature ##T## with ions of charge number ##Z##. 1. Explain the physical origin of bremstrahlung radiation 2. Represent the expected spectra (shape and...
  13. Javier Lopez

    I Stopping power for a proton ion gun through a Boron-11 sheet 1mm thick

    Hello, I need the stopping power for a proton ion gun through Boron-11 sheet 1mm thick. I have the following table obtained from here: https://www-nds.iaea.org/stopping/stopping_hydr.html Where the unit is in 1-15*eV*cm2/atom: Then I calculated for 600keV protons at table 5.1eV*cm2/atom. I...
  14. S

    How to calculate power using amps drawn?

    Is there a formula that I can use to calculate the HP a motor is actually making if all I have is amp draw? I am trying to size a gearbox, but the customer has no idea what torque is needed. All they know is the motor is drawing 5 amps when it spikes and 3.5 amps when it is running. I am...
  15. Mzzed

    Connect isolated ground to Earth?

    I am currently working on a high power class E amplifier which will sit inside a metal enclosure. It is powered by two power supplies - both are isolated but one of the power supplies is mounted in the same enclosure. The power supply itself is in a metal case and that case is connected to...
  16. CM CHAMPAK

    Launching satellites using electromagnet power

    Why can't we launch satellite by using electromagnet power?
  17. S

    Fraunhofer Diffraction Pattern Ratio of Power Densities

    Homework Statement Find an approximate expression for the ratio of the power densities at the principal maximum to that at the first secondary maximum on either side, in the Fraunhofer diffraction pattern of an N-slit multiple aperture. Assume that the slits are much narrower than their...
  18. B

    How do I calculate the power of a generator in terms of speed?

    Hi, here I am again. This is also related to my previous threads. My question is: How do I calculate the power of generator in terms of speed(rpm) from a drive system (such as belt and chain drives)?
  19. F

    Power line EMI filter + feedthrough filter for a Faraday cage

    Dear forumers, I need a 50hz 250VAC power line filter for an EMI shielding faraday cage. The filter should work between 100khz and 20ghz, attenuation should be >=60dB between 1mhz - 5ghz. Regular power line EMI filters like this don't seem to go that high (only up to a few hundreds of mhz...
  20. T

    Calculating Laser Power from Temperature Rise, Time, and Target Mass?

    Hi Everyone! There is a type of CO2 laser cutter power meter on the market (Product link removed) The meter uses a block of black anodized aluminum bonded to the end of basically a mechanical meat thermometer, and has a zero adjustment on the back of the face to set the base temperature to...
  21. B

    Gaming PC in my 2018 Kenworth T680 Truck -- Power Issues?

    Hello I'm trying to set up my gaming computer in my 2018 Kenworth T680 but having power issues. Both with the monitor and the tower. But mostly the monitor. I realize the power inverter is likely incompatible with monitor and tower PSU. I need a workaround. Issue: Monitor works interminitly for...
  22. Mr Davis 97

    I Complex exponential to a power

    Say I have ##e^{2\pi i n}##, where ##n## is an integer. Then it's clear that ##(e^{2\pi i})^n = 1^n = 1##. However, what if replace ##n## with a rational number ##r##? It seems that by the same reasoning we should have that ##e^{2\pi i r} = (e^{2\pi i})^r = 1^r = 1##. But what if ##r=1/2## for...
  23. cnh1995

    Electrical Network Problem: Power Transfer

    Homework Statement Homework Equations P=V2/R For maximum power transfer, Rload=RThevenin The Attempt at a Solution I know the efficiency is 50% during maximum power transfer. So when all the sources are acting simultaneously and ( at the same time) R=Rth, maximum power will be dissipated in...
  24. P

    Radius of Convergence and Power Series Expansion Around Multiple Values

    Homework Statement Suppose we are given the power series expansion ##f(x) = -\sum_{n=1}^{\infty} \frac{x^{n}}{n} ## which converges for |z|<1. What is the radius of convergence? Sum this serie and derive a power series expansion for the resulting function around -1/2, 1/2, 3/4 and 2. The...
  25. K

    Can a Car Battery and Charger Replace a UPS for Powering Electronics?

    Let's say you have a UPS 550 Watts (1100 VA). How much current or watts does the unit itself used? This is important when your source itself is limited by the wiring.. let's say all your computers total 500 Watts and the wiring is sized for roughly that.. Would the UPS draw more current or...
  26. bgm

    Efficiency of Base Load Power Plants

    interested in efficiency metrics with regard to our base-load infrastructure... this information is not readily available. I think that renewable stuff has its place only after we make the most of our base plants with load shifting. The base plants exist, and they waste energy. I simply do not...
  27. Spinnor

    I ....Alternatives to Inflation in Primordial Power Spectrum

    Unique Fingerprints of Alternatives to Inflation in the Primordial Power Spectrum "Massive fields in the primordial universe function as standard clocks and imprint clock signals in the density perturbations that directly records the scale factor of the primordial universe as a function of...
  28. Another

    Problem about electric potential and power transmitted down a cable

    When to use ## V =-\int E ⋅ dl ## or ## V =\int E ⋅ dl ## ? When i use ## V =-\int E ⋅ dl ##. i can not show that P = IV because ##\frac{ln \frac{b}{a}}{ln \frac{a}{b}} ≠ 1## But the solution use ## V =\int E ⋅ dl ## I'm concerned about using "minus" .
  29. TechTree

    Is power lost in an AC adapter?

    Hello, so I'm rather new here and I was wondering when I plug a USB device into an AC adapter, such as a phone how does it output exactly 5.2V and 2A? I'm aware that it goes through a transformer and rectifier but I heard somewhere that when the voltage is reduced the current is increased? Does...
  30. B

    How can we calculate the power of a heating element?

    To be more specific, if i have to heat water 300l of water in one hour. What should the power of a heating coil?
  31. M

    How to find the expression for current and power in an inductor

    Homework Statement A voltage of V = V_0 sin(\omega t) is applied to an inductor. Find an expression for the current and hence the power. Homework Equations I have used the equation: V = -L \frac{di}{dt} and for power: P = IV The Attempt at a Solution I tried to find I(t) by integrating...
  32. K

    Why is my CPU usage so high when opening multiple web pages on Microsoft Edge?

    I opened about 30 Microsoft Edge web pages.. the CPU usage can reach 75%. Why is there so much CPU usage for opened web pages? My processor is Intel Corei5 3.2 Ghz and 16 Gigs of DDR3 RAM.
  33. zeronem

    Is the Power of Two Sets Theorem Valid in Introductory Real Analysis?

    Just wanted to know if the work is sound and logical on my paper posted above. I realized I probably should have included notation for the power of the sets. This is my first attempt at theorem proving in Introductory Real Analysis. I realize now that I’m starting into a subject that...
  34. H

    B Gravity Power: What Gives It the Ability to Accelerate Objects?

    What is the physical property that gravity has that enables it to make an object go faster or, if it is resting on the ground, have weight? In General Relativity (as I understand it) objects in free fall move in geodesics. Thus an orbiting satellite moves in the curve around the planet that is...
  35. Jerry Z

    Homework help: Uncertainty with negative power

    Question: A distance R is measured to be 3.400 ± 0.007m. What is the absolute uncertainty in R^−2? Attempted solution: Relative uncertainty: 2* (0.007/3.4) = 4.11E-3; R^-2 = 3.4^-2 = 0.0865 m^-2; Absolute uncertainty = R^-2 * relative = 0.0865 * 4.11E-3 = 3E-4 m^-2; Any help would be greatly...
  36. H

    What gives gravity its power to accelerate objects?

    What is the physical property that gravity has that enables it to make an object go faster or, if it is resting on the ground, have weight? That means it can do work: it gives objects kinetic energy. Where does that ability come from and where does the energy (the gravitational potential...
  37. J

    Power required to compress air in a gas turbine

    I'm looking for advice on how much power is required to compress air in a gas turbine engine - parameterised by degree of compression and mass flow. Normal gas turbine engines have exhaust turbine(s) on the same shaft as the air compressors. They bleed some of the exhaust energy to drive the...
  38. G

    Equation for the resolving power of a microscope?

    Hi I'm reading through a Quantum Mechanics textbook called Quantum Mechanics by Book by Alastair I. M. Rae and in the opening chapter it talks about the Heisenberg uncertainty principle and talks about how a measurement of position of a particle causes an uncertainty from the momentum due to the...
  39. B

    What is the difference between water power and turbine power

    What is the difference between water power and turbine power? Do they have the same formula?
  40. T

    What are benefits of Electricity of nuclear power plant

    Hello What are benefits of nuclear power plant electricity than hydro power generated electricity Does it cost less per unit any or the waveform is pure sine wave how engineer build it .
  41. M

    Automotive Max Power Output with Air-Fuel Ratio

    How can the slightly richer Air fuel ratio produce higher power while the temperature it produces is lesser than slightly leaner(slightly leaner than stoichiometric for best economy)? FYI:I understood that ,at the stoichiometric ratio(precisely slightly leaner due to fast operation of engine)...
  42. S

    AC Mains Power conditioner question

    Does anybody here have experience with whole house power conditioners? We live in an old neighborhood with old overhead powerlines, and it's been a rough fall for brownouts and other little transient "interruptions". I already have UPS's on delicate stuff (basement server, PC, home theater), but...
  43. pellman

    I Why is the Axiom of Power Set needed?

    In the Zermelo-Fraenkel axioms of axiomatic set theory we find: Axiom. Given any set x, there is a set such that, given any set z, this set z is a member of if and only if every element of z is also an element of x. Why is this needed as an axiom? why isn't it merely a definition? Under...
  44. Mzzed

    RF Power Meter / SWR Meter Equivalent Circuit

    I'm starting to get into RF electronics, and an upcoming project involves the use of a power meter / SWR meter. How do we model a power meter in terms of an equivalent circuit? i.e. is it just another impedance? or a transformer? or does it not effect the circuit at all, so we just don't include...
  45. G

    Power grid & generator questions

    Before I begin I have to note that my last thread of this kind got heavily moderated and closed because the moderators did not like the specific way in which I was formulating my questions, so now I want to clarify and reaffirm some of what I have learned through questions without making any...
  46. J

    Power generated by the steam turbine

    Homework Statement Shown in the figure Homework Equations W= (p2v2-p1v1) / (1-n) The Attempt at a Solution I am not sure where to start and where to use all the data given in the table. Please help. It would be nice if someone could explain the basic nature of the steam turbine, how it...
  47. J

    Power generated by the steam turbine

    Hello, I'm trying to solve a question, please help me.
  48. S

    Fundamental confusion about THREE-PHASE electric power setup

    Homework Statement Hello to everyone who's reading. :) I hope I posted this in the right place; while this is not exactly a homework problem, I am trying to improve my understanding of the background information before proceeding with course-style problems. This post is because I'm trying to...
  49. N

    High Power Amplifier for Acoustic Transducer

    Hi all I am in search of a Power Amplifier (preferably Solid state pulsed amplifier ) which is able to output around 340 Vrms across 25 ohm impedance load (acoustic transducer operating at approx 4.5 KW) in pulsed mode with duty cycle less than 1%, maximum pulse length of 5 ms and operating...
  50. G

    Power plant generator improvement

    I have looked over the types of generators used in most power plants (Hydro, Nuclear, coal etc) and with different sized and rotor rpm's they all basically share the same principle of operation if I'm not mistaken, which is that the rotor gets supplied via brushes and slip rings with a DC...
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