What is Phase: Definition and 1000 Discussions

In the physical sciences, a phase is a region of space (a thermodynamic system), throughout which all physical properties of a material are essentially uniform. Examples of physical properties include density, index of refraction, magnetization and chemical composition. A simple description is that a phase is a region of material that is chemically uniform, physically distinct, and (often) mechanically separable. In a system consisting of ice and water in a glass jar, the ice cubes are one phase, the water is a second phase, and the humid air is a third phase over the ice and water. The glass of the jar is another separate phase. (See state of matter § Glass)
The term phase is sometimes used as a synonym for state of matter, but there can be several immiscible phases of the same state of matter. Also, the term phase is sometimes used to refer to a set of equilibrium states demarcated in terms of state variables such as pressure and temperature by a phase boundary on a phase diagram. Because phase boundaries relate to changes in the organization of matter, such as a change from liquid to solid or a more subtle change from one crystal structure to another, this latter usage is similar to the use of "phase" as a synonym for state of matter. However, the state of matter and phase diagram usages are not commensurate with the formal definition given above and the intended meaning must be determined in part from the context in which the term is used.

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  1. nuclearfireball_42

    Can I determine the phase angle of this equation by using the sin function?

    I've got the answer for (a). It's k = 0.78 N/m. I'm having problems with (b). I know that the equation of displacement in this case should either be : x(t) = Asin(ωt + φ) or x(t) = Acos(ωt - φ) where A = amplitudeFrom what I understand, both the equation above should give the same result as...
  2. e101101

    I Phase Plane Diagram w/ Complex eigenvalues

    Is the spiral I drew here clockwise or counterclockwise ? What’s a trick to know whether it’s going CCW or CW. Thanks!
  3. B

    Phase difference between 2 points on a wave

    So to do this problem I need the relevant formula for phase difference which is this: I first need to find wavelength and this is lambda = velocity/frequency So lambda = 257/641 = 0.40093603744 m Hence phase difference (in radians) = 2pi * (2/0.40093603744) = 31.3 rads My concern is that...
  4. I

    Finding meaning in the Phase of the wavefunction

    Suppose ##\psi_{0}## is a properly normalised wavefunction with ##<x_{\psi_0} >## = ##x_{0}## and ##<p_{\psi_0} >## = ##p_{0}##. Define a new wavefunction ##\psi_{new}##(x) = ##e^{{-iqx}/{\hbar}}## ##\psi_{0}## What is the expectation value ##<\psi_{new}>## in the state given by...
  5. A

    Help with waveform control: frequency, phase and amplitude

    Hello, I am looking for a controller whether programmable or otherwise that could function as a drive and control circuit which would monitor a transformer output connected to a load and then drive an amplifier with a signal that is proportional to the needed one in order to control the output...
  6. Blakely42

    Potential Energy vs x phase diagram

    U(x) = - ∫Fdx = - (1/2)kx^2. T = (1/2)m(x')^2. E = (1/2)[m(x')^2 - kx^2]. We could write out the Lagrangian here, but the chapter this comes from (Taylor's Classical Mechanics 13.6) indicates we should probably write the Hamiltonian, H = T + U. As far as I can tell, this doesn't tell me a...
  7. V

    Python Phase shifting a measured signal directly in time domain

    I need to perform a phase shift for a measured time domain signal. The signal consists of around 1000 points. I wrote an algorithm for this in Python a while ago and it seems to work as intended, but now I noticed that the algorithm is actually unexpectedly slow. Is it so that phase shifting is...
  8. E

    B Understanding Phase Terminology in Wave Functions: A Guide

    Almost everywhere I've looked uses the term phase in different contexts, so I was wondering if someone could let me know whether I've used the right terminology for the different concepts. For a wave ##y = A\sin(kx-\omega t + \varphi)##, I was under the impression that The phase, ##\phi =...
  9. nima_kheradhoosh

    How can I apply a variable phase shift to an AC signal generated by a VFD?

    Hey fellas, I’m trying to apply a variable phase shift (0 to 180 degrees) on an AC signal generated from a Variable Frequency Drive (VFD). The frequency is variable and ranged between 10 and 50 Hz. the voltage amplitude is also variable between 10-50Volts (this shouldn’t be a problem I suppose)...
  10. jisbon

    Plano-convex lens with phase changes

    By drawing arrows, I can find out the following: Since they are in different phases, I get: ##2nt=m \lambda## for dark fringes. In this case, they want me to find the radius of curvature. I'm not sure what to really proceed on here. What I figured out so far is that I will be able to find the...
  11. J

    MHB Amplitude, Period, frequency and phase angle

    HELP! totally lost and confused with this question: A machine is subject to two vibrations at the same time. one vibration has the form: 2cosωt and the other vibration has the form: 3 cos(ωt+0.785). (0.785 is actually expressed as pi/4) determine the resulting vibration and express it in the...
  12. currently

    MATLAB Position-Velocity phase plane portrait in MATLAB?

    For example, how would I graph a Position-Velocity phase portrait of a nodal sink or spiral sink? Given form of mx'' = -cx' - kx + βx^3.
  13. C

    Proof of second-order phase transition for a Van Der Waals Gas

    How is it proved that Van Der Waals gas is a second order phase transition? The second order derivative of the pressure (P ) with respect to volume ( V ) don't have a discontinuity ( except at point V = Nb , but the pressure is not existent for V<=Nb ). So how come Van der waals gas describes...
  14. Uchida

    Does radiation pressure depend on the wave phase?

    Hello to all, Does radiation pressure depends on the wave phase of the electromagnetic wave hitting a surface? Or, can the radiation pressure be modeled as a sin/cos wave function, where force due to radiation pressure F = P/c would be the average over one cycle? (P = power, c = light speed...
  15. jeon3133

    What is the effect on the Berry phase?

    Homework Statement : Consider a Hamiltonian H[s ] that depends on a number of slowly varying parameters collectively called s(t). What is the effect on the Berry phase γn[C] for a given closed curve C, if H[s ] is replaced with f[s ] H[s ], where f[s ] is an arbitrary real numerical function of...
  16. C

    Can phase shift keying delay a wave further?

    See fig(a), S1Q=7lambda S2Q=9lambda I think since source S2 is lagging behind. So, we should add the phase 4pi instead of subtracting it from the cosine function. Wouldn't subtracting the phase further delay the wave more.
  17. Riotto

    I Single-particle phase spaces for a system of interacting particles

    For a system of interacting particles, is it possible to define single-particle phase spaces? If not, why?
  18. E

    Help with the phase of the solution for a driven oscillator

    My question also applies to the damped driven oscillator, however for simplicity I will first consider an undamped oscillator. The equation of motion is $$-kx + F_{0} \cos{\omega t} = m \ddot{x}$$ or in a more convenient form $$\ddot{x} + {\omega_{0}} ^{2}x = \frac{F_{0}}{m} \cos{\omega t}$$The...
  19. Diracobama2181

    Van Der Waals Phase Transition

    Not sure where to actually start. Do I need to do a virial expansion? Any tips on on where to start would be greatly appreciated.
  20. C

    Phase space volume with a potential (microcanonical ensemble)

    I don't know how to solve that integral, and to calculate the number of microstates first, then aply convolution and then integrate to find the volume of the phase space seems to be more complicated. Any clue on how to solve this? Thank you very much.
  21. S

    3 phase alternator is generating a voltage, but no current

    I made a permanent magnet alternator out of a 3hp 3 phase induction motor. I am getting voltage, but no current at all. The alternator is wired delta and feeds a capacitor bank wired in a wye, to create a neutral. I have even tied the neutral into the alternator and still no current. I connected...
  22. J

    400 volt 3 phase 16 amp machine -- can it be used in the US?

    Maybe you can please give advice. I have a coffee roaster here in New Zealand I would like to bring to the US. It is 400 volt 3 phase 16 amp. It has a blower, a heater and computer components to run it. It is like a very large popcorn machine. Can this work in the US?
  23. DryRun

    Calculate the phase angle between two sinusoids

    I am trying to do exactly what was stated, by finding it with calculations only, so, without having to draw the curves. Is that possible? Here is my attempt: v1(t) = -10cos(wt + 50) and v2(t) = 12sin(wt-10) v1(t) = -10cos(wt + 50) becomes v1(t) = -10sin(wt+50+90) = v1(t) = -10sin(wt+140) Now...
  24. S

    Phase difference between two points

    I find λ first and I get λ = 3/10 m phase difference = ##\dfrac{2 \pi (1) }{\dfrac{3}{10}} = 6.7 \pi## Answer key = B What is my mistake? Thanks
  25. Utg

    A CP Violation & Phase: Explained

    Hello! I have heard many times that CP violation in the SM is due to the presence of phase in the CKM matrix. Can somebody explain how phase is related to CP violation? Thanks!
  26. F

    How is absorbed thermal energy invested during a phase change?

    Hello, I was pondering on the well known fact that a certain amount of substance, when absorbing heat, increases in temperature up to a certain temperature and then phase (state) transformation takes place. Any energy supplied at that point does not increase the temperature any further but is...
  27. ChrisXenon

    I E & B field phase relationship in EMR

    Common diagrams for the magnetic and electric field components of EMR show the fields at right angles in space with peaks aligned along the axis of propogation, for example Wikipedia here: https://en.wikipedia.org/wiki/Electromagnetic_radiation. However, Faraday's law says the E field depends...
  28. G

    Electrical Options for powering a three phase machine

    The motor from this fine, old and very heavy machine is designed to take UK 3ph, 415V. There are only three connections inside, and the nameplate says it’s wired in star. I have stripped it down and cannot locate the star point. I was hoping to rewire it to delta, and run it with a 1ph/240V to...
  29. warhammer

    B Shifting of a Cosine Curve with negative phase angle values

    Continuing on from the summary, the chapter has given a graphed example. We are shown a regular cosine wave with phase angle 0 and another with phase angle (-Pi/4) in order to illustrate that the second curve is shifted rightward to the regular cosine curve because of the negative value. Now, my...
  30. H

    I Is an atomic electron transition a phase transition?

    Is atomic electron transition a phase transition? https://en.m.wikipedia.org/wiki/Atomic_electron_transition
  31. Baibhab Bose

    Phase transition between two phases with different Cv

    I actually can't figure out what kind of phase transition it is and how to proceed through..!
  32. S

    How to calculate the transition temperature in this problem?

    Summary: The transition Sn(s, gray) ⇌ Sn(s, white) is in equilibrium at 18°C and 1 atm pressure. If ΔS = 8.811K mol for the transition at 18°C and if the densities are 5.75 g/cm3 for gray tin and 7.28 g/cm3 for white tin, calculate the transition temperature under 100 atm pressure The...
  33. PainterGuy

    B Are there any points other than the origin where cosines are totally in phase?

    Hi, This question just came to my mind and I thought I should confirm it. Are the cosine functions with the same amplitude but different frequencies are totally in phase at any other point other than the origin? The frequency, f, could be anywhere between 0 < f < ∞. I'm sorry if the answer is...
  34. D

    50Hz 3 Phase Circuit - Twisting to reduce EMI?

    I have done the maths to work out the Induced Voltage on a communication cable, from a bunch of 3 phase circuits in a panel - with the minimum distance between them I calculated it to be about 1.5nV; but for a larger system where there could be larger loads on the cables I was thinking about...
  35. merlyn

    The phase of electric and magnetic forces in a photon.

    I'm curious if someone help me understand why the electric and magnetic forces are IN PHASE at right angles to one another? Should they not be 90 degrees out of phase in order to conserve energy? I do understand they are in phase but why? Thank you all for your time. Merlyn.
  36. M

    A Golden ratio fractal phase conjugation

    So, I recently heard about the Golden ratio fractal phase conjugation and I was wondering if it could possibly explain the solar system formation. Meaning, if you can imagine a torus energy dynamic shape (with the sun in the middle) maybe it could be explained by this theory?
  37. F

    Engineering Draw the magnitude and phase angle of a voltage in this AC circuit

    My solution is attached below. I am not sure if my answer is correct or not , I want to confirm it.
  38. DaniV

    A Mapping the Phase Space of Type II Superconductors

    Due to my lab work I want to try map the phase space that created with critical external magnetic field H_c and the critical current J_c through the superconductor of type II. the critical transition happen from the Abrokosov phase to the non-superconductor phase, occurred by the fact that in...
  39. D

    I have tried building a phase shift oscillator, but it won't work

    I built a phase shift oscillator, but it Won't work. I visit the website https://www.google.com/url?sa=t&source=web&rct=j&url=https://en.m.wikipedia.org/wiki/Phase-shift_oscillator&ved=2ahUKEwiV4Y-26OHiAhUClawKHQhACO8QFjANegQIChAG&usg=AOvVaw0YoHKumGz0Xl3fYKtIRdFa and copied the schematic I saw...
  40. T

    Enthelpy vs Internal Energy in Phase Change

    Is there anybody who can advise wether the heat lost / gained during vaporisation, is best calculated from enthalpy, or from internal energy, in the steam tables? I am trying to establish the increase in the volume of milk when the temperature is raised by adding saturated steam at 1 bar (1...
  41. shahbaznihal

    I Phase space density function and Probability density function

    I am reading a text which talks about the WIMP speed distribution in the galactic halo in the frame of the Sun and Earth. The point where I am stuck it is trying to explain the concept of Gravitational Focusing of WIMPs at the location of the Earth due to the gravitational well of the Sun...
  42. S

    B Phase shift in Mach-Zehnder interferometer

    I'm confused by the phase shifts in a Mach-Zehnder interferometer because I keep finding two different explanations. One explanation (for example, given on Wikipedia, but also elsewhere) states that on each reflection, the phase shift is 180 degrees, but only, if light is reflected from the...
  43. C

    Molecular Orbits....what exactly is meant by orbitals having phase?

    Hello. I understand constructive/destructive interference for waves in general. But why do orbitals have phase? What is meant by phase for an orbital? What is the phase describing? Isn't the wave function describing where you are likely to locate the electron? Why is one positive and one...
  44. Mcp

    Phase diagrams for fractional distillation

    https://www.chemguide.co.uk/physical/phaseeqia/idealpd.html#top I learned about phase diagrams involving partial Vapour composition, temperature and composition of binary solutions from this website. You can find it if you scroll down to a little above the end First it considers a binary...
  45. Pierson5

    Complex impedance and phase angle of a circuit

    I've attached my work below. The numbers seem odd to me though. Are my equations correct? Is the phase angle really (0/12)? If so, what are the implications of that?
  46. K

    Electrical Help with making a heating element with a 3 phase power supply

    hi everyone. my uncle currently has a big "cylindrical rolling cooking pot" (imagine a cement mixer with burners at the bottom) that he uses to cook his stuff, ie sesame seeds. this cooking pot currently runs on gas. as he has been facing some issues with the gas supplier, he intends to...
  47. AwesomeTrains

    I Help understanding the formula for the total phase shift of a waveplate stack

    I have problems deriving a formula in a paper I'm reading for a project. The paper is about putting a number of waveplates in series rotated relatively to each other to form a tuneable broadband waveplate. For the i-th waveplate the jones matrix is given by: $$ J_{i}(\delta_i, \Theta_i)=...
  48. D

    US 2-phase conversion to EU one phase

    I recently bought a machine from china. The power requirements are 220v single phase with 4 motors that draw about 16A collectively. The factory told me 5.5KVA as a minimum power source. If I use a step up transformer from 120v this means 45A max current draw. US 220v(240v) is really 2-phase...
  49. A

    Relationship between k and orbital phase of solid state?

    I understand that quantum objects have wave and particle properties. I know that k = 2π / lamda. I am simply not understanding the x-axis of a bandstructure plot of E(k) vs. k. I've read parts of a book by Roald Hoffman on this subject. In the book it is shown that there are infinite chain of...
  50. E

    State three reasons why the phase difference between two light waves

    what would cause the phase difference ?
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