Phase Definition and 1000 Threads

  1. B

    I Can a phase space be subject to change, and if so, what are the implications?

    I'm asking if space space is subject to change, if not, why not, and if so, then would it be subject to a subsequent phase space that describes that? Let us make a phase space for a deterministic time evolved dynamic system of three spatial dimensions. Since the actions of the system and the...
  2. R

    Out of phase light/photons, would it be measurable?

    With sound you can create out of phase signals and they cancel out, this is not possible with light as it does not interact like sound does. If it was possible to create two light sources in that were exactly 180 degrees out of phase with each other and aim them at a common point (eg an...
  3. W

    Engineering Phase relationships in Thévenin circuit

    Homework Statement 2. Homework Equations 3. The Attempt at a Solution [/B] For part (c), should the phasor diagram just have everything on a straight line, save for the Rt and Vrt? Honestly not sure how to attempt part (d) as we never really covered phase relationships in lectures, just...
  4. Jabbar_B

    I Viscosity, two immicible phase flow, wettabilility

    If the single phase flows on the inclined surface and this phase (let's say water) is wetting the surface then closest layer to the surface will be bounded and will not move. And velocity of flow will be in inverse proportion with viscosity of the fluid. If now the second phase is introduced...
  5. L

    Position vs time graph simple harmonic motion phase constant

    Homework Statement http://imgur.com/a/FDfAp What is the phase constant? Homework Equations x(t) = A*cos(ωt+Φ) The Attempt at a Solution If I'm not mistaken at t = 0 the graph starts at half the amplitude or 5. Also the amplitude of this graph is 10, and at t = 0 angular velocity is also 0. 5...
  6. J

    Find V2 in Single Phase Transformer

    1. Homework Statement Find V2. Everything else is available in the picture Homework Equations r1=r1+a^2*r2 x1=x1+a^2*r2 z2=a^2*r2 I1=vp/z2+r1+x1 The Attempt at a Solution So I have used the first three formulas but it's the last one I am getting stuck on. Since my x1 is an imaginary number...
  7. O

    3 Phase Systems Theory and Procedure -- Determining Average Power

    Homework Statement Consider the 3 following Scenarios: 1. 2. rms value of line voltage is 208 V Three equal impedances, 60 +j30 W each, are delta-connected to a 230-V rms, three-phase circuit. Another three equal impedances, 40 +j10 W are wye-connected across the same circuit at the same...
  8. binbagsss

    Deriving continuity equation of phase space in Statistical Mechanics

    Hi, So I am aiming to derive the continuity equation using the fact that phase space points are not created/destroyed. So I am going to use the Leibiniz rule for integration extended to 3-d: ## d/dt \int\limits_{v(t)} F dv = \int\limits_{v(t)} \frac{\partial F}{\partial t} dV +...
  9. D

    Find effective value and phase shift for the current I

    Hi guys! I am wondering if someone can help me with an assigment i got, i would appreciate if someone could help me with it. Find effective value and phase shift for the current I in the link the tip is to use the superposition theorem http://imagizer.imageshack.us/a/img924/3673/R5qIAN.png
  10. P

    Creating a 31.4KHz Phase Sweeper for Antenna Array

    I am trying to create a phase sweeper at 31.4KHz(and constant 5V) for a small antenna array that consists 2 antennas. If I can create 2 signals with a frequency difference < 1Hz it's okay too(It will be nearly same) as long as I can control that difference because I need to change phase at a...
  11. O

    What is the Phase Angle of an LRC Circuit with Given Components and Frequency?

    Homework Statement A 35 mH inductor with 1.0 resistance is connected in series to a 20 µF capacitor and a 60 Hz, 40-V (rms) source. Calculate the phase angle. Homework Equations tan φ = (XL - XC) / R The Attempt at a Solution Solving for φ: φ = tan -1 [(XL - XC) / R] XL = 2πfL = 13.194 Ω...
  12. A

    Resultant equation of two identical out of phase waves

    Homework Statement Two identical traveling waves, moving in the same direction, are out of phase by π/5.0 rad. What is the amplitude of the resultant wave in terms of the common amplitude ym of the two combining waves? (Give the answer as the ratio of the total amplitude to the common...
  13. S

    I Berry phase without a magnetic field

    It is common to calculate Berry phases for quantum systems in, for example, a magnetic field. In this case we compute the Berry phase ##\gamma## using $$\gamma[C] = i\oint_C \! \langle n,t| \left( \vec{\nabla}_R |n,t\rangle \right)\,\cdot{d\vec{R}} \,$$ where ##R## parametrizes the cyclic...
  14. S

    I Phase factors of eigenstates in time-dependent Hamiltonians

    For a time-dependent Hamiltonian, the Schrodinger equation is given by $$i\hbar\frac{\partial}{\partial t}|\alpha;t\rangle=H(t)|\alpha;t\rangle,$$ where the physical time-dependent state ##|\alpha;t\rangle## is given by $$|\alpha;t\rangle =...
  15. Jadaav

    I RA and declination of Sun & phase of Moon program

    Hello there, I want to write a fortran program which gives me the right ascension and declination of the sun and the phase of the moon when a date and time is given. I just want to know how to write it and if there are any references that can help me. Thanks, Jadaav.
  16. C

    I Phase transitions university classes

    There's something that I'd like to know and haven't been able to find in any book: 1.- Is the number of second order phase transition university classes known? 2.- Do we know quantitatively know the behavior of all such second order phase transition university classes? 3.- Do we know the...
  17. Ravi Singh choudhary

    Gibbs phase rule use for wet vapour

    I have a doubt regarding gibbs phase rule in thermodynamics.. It says the number of independent intensive properties required to specify the state of a system is F=C-P+2 where C is number of components and P is the number of phase.. So for a water and water vapour system, C=1, P=2 . So F=1. If...
  18. Kirmandarren

    Propane phase change in a container

    If I had a container containing 10 bara of nitrogen, and pumped in liquid propane at room temperature would the propane boil? If I carried out the same experiment but this time at 5 bara, what would be the temperature of the material once the propane had completed its phase change i.e would it...
  19. T

    Find the phase difference of two oscilliators given a graph

    Homework Statement The two oscillators each have the same mass. Use Fig. 4.1 to determine (i) the phase difference between the two oscillators (picture attached) Homework Equations Subtracting to find the horizontal shift The Attempt at a Solution I found the two points where both graphs...
  20. S

    I Is the definition of a phase arbitrary?

    Gibbs phase rule says f = r-M+2 with f: thermodynamic degrees of freedom; r: number of components; M: number of phases I wonder whether the defintion of "phase" is restricted or almost arbitrary. For example, consider a system of H2O, O2 and H2 in a closed vessel. Let there be the contstraint...
  21. A

    Phase Difference Between Two AC Signals: Can it be Zero?

    If i have two sinusoidal ac signals of 220V with the different phase angle i.e. there is some phase difference between them. Then can i make the phase difference zero?? Please tell
  22. U

    Understanding phase shift w/ time of 2 different frequencies

    Hi all, I hope this question is of an acceptable format to ask about here. I'm just having trouble trying to get a conceptual understanding of the following. I've been told that if I'm given two different frequencies that are completely in phase at time equal to zero, then I can find their...
  23. ShayanJ

    Phase space of spherical coordinates and momenta

    Homework Statement [/B] (a) Verify explicitly the invariance of the volume element ##d\omega## of the phase space of a single particle under transformation from the Cartesian coordinates ##(x, y, z, p_x , p_y , p_z)## to the spherical polar coordinates ##(r, θ, φ, p_r , p_θ , p_φ )##. (b) The...
  24. D

    Superimposing 2 sources of light slightly out of phase

    Assuming for now a simple photon particle model for light, where you have a stream of photons traveling with a certain frequency. Picturing this in my head on a number line, with just 3 photons at a time, and let's just say the wavelength is 1 and speed is 1, and at time t=0 we have a photon at...
  25. S

    I Gaussian integration for complex phase

    I would like to prove that ##\displaystyle{\int dx'\ \frac{1}{\sqrt{AB}}\exp\bigg[i\frac{(x''-x')^{2}}{A}\bigg]\exp\bigg[i\frac{(x'-x)^{2}}{B}\bigg]=\frac{1}{\sqrt{A+B}}\exp\bigg[i\frac{(x''-x)^{2}}{A+B}\bigg]}## Is there an easy way to do this integration that does not involve squaring the...
  26. B

    A Berry phase and gauge dependence

    Hi, I have a question that has been bugging me recently. It's about the berry phase and something that I find contradictory. One can see that it is possible to get rid of 2π x (integer) part of the Berry phase by means of a gauge transformation. This in general applies to phases (gauge...
  27. moenste

    AC through the wires, forces acting in/out of phase currents

    Homework Statement Two parallel wires have currents passed through them which are in the same direction. Draw a diagram showing the directions of the currents and of the forces on the wires. Alternating currents are now passed through the wires. Explain what forces would act if the currents...
  28. A

    What are the units of Kp, (Gas phase equilibrium)

    I know the units of Kc are mol/liter. The units of Kp are either mol/atm or just atm. Not really sure. I get mles atm and liters in my answer when i solve. Pretty weird
  29. teetar

    Determining phase shift of two frequencies

    Homework Statement I'm given two frequencies: 4,000 Hz, and 5,000 Hz. They are completely in-shift at time ##t=0##. I am to find the time it takes them to get completely out of phase. Homework Equations The Attempt at a Solution I've not gotten waves very well thus far in physics. My teacher...
  30. Tafe

    Quantity of heat, phase change of ice to water

    Homework Statement A 1x106 kg piece of ice is placed into a lake. How much heat is taken from the lake to raise the temperature of the ice from 0 °C to 1x10-20 °C? How much volume does the lake increase by? Latent heat for water is 334x103 J/kg Homework Equations Found in my textbook, cice =...
  31. T

    Why Does the Phase Shift Oscillator Frequency Drop with the TL072?

    1. The problem FIGURE 4(a) shows the circuit of an oscillator and FIGURE 4(b) gives the gain and phase response of the op-amp used. When the circuit was simulated in PSpice using an ideal op-amp, the circuit oscillated at the designed frequency. However when the ideal opamp was replaced by the...
  32. Tazerfish

    Phase difference between magnetic and electric field

    When solving the differential equations for an electromagnetic wave you get out that the electric and magnetic field oscillate in phase. But when considering a oscillating dipole, the electric and magnetic field at a point close to the dipole are a quater period out of phase. Can someone please...
  33. Clara Chung

    B Why do water waves not undergo a phase change when they hit a fixed wall?

    Why won't water wave undergo a phase change of pi when it propagates to a fixed wall just like a pulse of string does.
  34. S

    Phase change material steady melt temp, like ice water?

    Ice melting in a box has the water coming off it at a temp just above freezing until all the ice is gone. Are all phase change materials pretty much the same, with their immediate containment container exterior staying pretty much just above their phase change temp until all the PCM inside has...
  35. kolleamm

    Where can I find a controller for a 3 Phase AC motor?

    I'm working on a project with a team in building a motor. My task is to find a controller for the motor, but I haven't had much luck. Here are the specs for it : Permanent magnet synchronous motor, 3 phase 8 pole 2 layer winding 100 kw power 400V The motor is AC. If somebody can even point me...
  36. B

    Lossless transmission line characteristic phase constant

    Homework Statement A lossless transmission line has an inductance of 9.0 nH / m and a capacitance of 3.6 pF / m. a) What is the line's characteristic impedance? b) Calculate the phase constant of a frequency of 1 GHz. Homework Equations Equation of characteristic impedance of a transmission...
  37. K

    Understanding the Concept of Phase Velocity: Explained Simply

    Hi all, I have a difficulty to understand the concept of phase velocity of a wave packet. I read some materials online and my text, I didn't find a very straightforward explanation on this concept except the math definition. I also read some threads from this forum, but still have some...
  38. H

    I Is an integral over phase space reasonable?

    In statistical physics, the partition function should be calculated in the whole phase space.This is finally an integral over the phase space, like ∫d3Nqd3Np... The problem is that the integral covers some cases that different particles have the same generalized coordinates and momenta. So, is...
  39. T

    Phase constant sign (quick question)?

    Homework Statement A = 20 cm Given the graph, what is the phase constant(in degrees)? (I have already solved for amplitude and frequency) Homework Equations x(t) = A cos (wt + ϕ) The Attempt at a Solution x(t) = A cos (wt + ϕ) Taking from t = 0, we find: 10 = 20cos(w*0 + ϕ) 10 = 20cos(ϕ) 1/2...
  40. F

    Space vector analysis of 3 phase -- stuck on a concept

    I am trying to understand space vectors in 3 phase machines. If you have a balanced 3 phase system, the 3 phasors of voltage, current or whatever... should sum to 0. i<0 + i<-120 + i<-240 = 0. But in this image of a rotating space vector ...
  41. H

    Why are position and velocity independent variables in a phase space?

    Why do we take a particle's position ##x## and its velocity ##\dot{x}## as independent variables in a phase space when they are dependent in the sense that given the function ##x(t)##, we can get the function ##\dot{x}(t)##? I'm thinking they are independent variables but not independent...
  42. DrClaude

    Phase transition in rotating balls

    A very neat video showing a phase transition in rotating balls in a cup. Serves as a good analogy to other phase transions.
  43. N

    Group velocity and phase velocity

    Could you please explain the derivation of group velocity = dw/dk I read ut here https://en.m.wikipedia.org/wiki/Group_velocity Is it approximation, if so under what circumstances
  44. C

    B For oscillations, why do we use angles in waves and oscillat

    For example, the term angular frequency, it units is radian per second. For phase, it is also measured in radians or degrees, why is that? Why is the math the same when you use angles to describe oscillations?
  45. Planobilly

    Using 400V 50Hz 3 phase motors with 240V single phase 60Hz

    Hi, We have a machine from Europe with three 400V 50Hz 3 phase motors. Assume we only have 240V single phase available. There may be 480V single phase available. I don't currently know how many poles the motors have. Assume they are not made for both 50Hz and 60Hz as some are. Power consumption...
  46. T

    Three phase power meaurement questions

    I have a few questions regarding three phase power measurement Three Watt-meter method: Balanced load: What would happen if the neutral where removed ?, my guess is that it wouldn't make a difference because the neutral doesn't carry any current Unbalanced load: Same question as above Two...
  47. Kfir Dolev

    I Is it possible to build a phase shifter from RLC components?

    Say you have a circuit component with impedence Z(\omega). Is it possible combine it in some way to resistors, capacitors, and inductors, so as to shift the phase of the impedance by a constant?
  48. T

    480V Split phase / 400V Threephase (AUS)

    HI there, First post here, I hope I can get out into the forum and provide some answers to you in the future. I am an Electrician here In Australia and spent my career so far in Industrial. Currently I have a job which is putting me to the test so I thought someone might be able to offer some...
  49. E

    Entropy Change in a Reversible Process multiple phase change

    Homework Statement (a)How much heat must be added to a block of 0.120kg of frozen ammonia initially at 100oC to convert it to a gas at 80oC given the following information? (b) assuming this could be done using a reversible process what would be the total entropy change associated with this...
  50. kostoglotov

    Will an infinite impedance cause no phase shift?

    Homework Statement imgur link: http://i.imgur.com/0Zc8nQe.png Homework Equations Y-Delta transformations The Attempt at a Solution Since it's a proof, I can't check the answer in the back. What I did: I transformed the three impedances in their delta config to a Y config, and my TI89...
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