Phase Definition and 52 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. maxelcat

    Standing wave, phase and antiphase

    I think I understand that points P and R are pi radians out of phase - reaching their max/min at the same time. But are P and Q in anti phase? What is antiphase exactly - is it when they are 180deg out of phase - or is it when they are anything other than totally in phase? I seem to find...
  2. person123

    Dataset for Water PVT Diagram

    I'm looking to create a little webapp where the user can see the 3-D PVT phase diagram, giving the user functionality like orbiting the surface and moving a point along the surface. (I attached an image of the surface I'm referring to). To do that, though, I would need the data defining the PVT...
  3. D

    I Physical interpretation of phase in solutions to Schrodinger's Eqn?

    Hello all, So I've been working through the solutions to some simple introductory problems for the Schrodinger Equation like the infinite square well, and I'm trying to make sense of how to think about the phase component. For simplicity's sake, let's start off by assuming we've measured an...
  4. D

    Water phase diagram

    I notice that water phase diagrams provided online always seem to show a rather linear behaviour for the solid-liquid boundary (and an extremely steep slope). How is this modeled mathematically? Say we use the Clapeyron equation with ΔH and ΔV_m being constant, as online example problems (meant...
  5. Rahulx084

    Thermodynamic Phases

    #Can somebody please explain what is the difference between single phase and homogeneous phase in context with thermodynamics? #Also in the fundamental relations in thermodynamics like dg=vdp-sdT , it says this is applicable to homogeneous phase of constant composition. Isn't this equation...
  6. entropy1

    Randomizing phases of harmonics

    Suppose I decompose a discrete audio signal in a set of frequency components. Now, if I would add the harmonics I got, I would get the original discrete signal. My question is: if I would randomize the phases of the harmonics first, and then add them, I would get a different signal, but would it...
  7. 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...
  8. C

    How does the phase noise of the LO effect IF accuracy?

    Hi, I have a roughly 1.1 GHz signal to be downconverted to 100 MHz by mixing it with a 1 GHz local oscillator. I am not sure how to choose the performance of the LO. In particular: let's assume the LO has a jitter of 100 fs rms. At 1 GHz this corresponds to a frequency error of 100 kHz. Does...
  9. zehkari

    Double slit intensity question

    Homework Statement Homework Equations (1) Φ = 2π*(dsinθ/λ) (2) Itotal = I0 cos2(Φ/2) (3) Itotal = I0 cos2(πdy/λR) λ = 585 * 10-9 m R = 0.700 m d = 0.320 * 10-3 m y = ? The Attempt at a Solution a) I used eqn (1) and divided the total oscillations by a complete oscillation to find the...
  10. B

    Phase shift and circular polarization

    What is the phase difference between the right circularly polarized and left circularly polarized light of the same amplitude? And how do you calculate it?
  11. Y

    Phase angle and Phase in Simple harmonic motion

    I'm a teacher at a Senior High School in Indonesia. I have two Senior High School physics books (Indonesian book) written about simple harmonic motion formula: y = A sin θ = A sin (ωt + θ0) = A sin 2πφ = A sin 2π (t/T + θ0/2π) phase angle = θ = ωt + θ0 phase of wave = φ = t/T + θ0/2π But I...
  12. Cathr

    Electromagnetic wave equation - phase and amplitude

    There are some things that confuse me about electromagnetic waves, and I haven't found good answers anywhere. Consider the following equation: E=E0 e i(wt-kx) (here E and E0 are vectors, I couldn't find the right symbols). The things that confuse me are the following: 1° We say that the power...
  13. entropy1

    I Frequency spectrum of phase shift

    What does a 180 degree phase shift of a sinusoidal in a signal do to the frequency spectrum of the signal?
  14. nomadreid

    I Phase, Bloch sphere versus Feynman path

    I am pretty sure that I would be comparing apples and oranges in this question, but as I usually learn something from the responses telling me in detail that my question is silly, here goes: Does the phase used as a weight in Feynman's path integral formulation (i.e., the quantum action S in...
  15. T

    Phases of hydrocarbons in a compressed gas cylinder

    I'm currently in the process of selecting gas mixtures to calibrate a gas chromatograph. One of the gas mixtures I'm interested in has the following composition by percent volume: methane (CH4): 95% carbon dioxide (CO2): 1% butane (C4H10): 1% acetylene (C2H2): 1% nitrogen (N2): 2% The gas...
  16. A

    Inverse phase sound wave where does energy go?

    2 sound waves that are mathematical polarities cancel each other out according to my audio engineering book. I thought energy cannot be destroyed, just changed. Am I wrong? What happens to the energy? Same question could be applied to matter and anti matter right?
  17. SchroedingersLion

    I Mixed states vs pure states - physical POV

    Hey guys, I am having issues with understanding the physical nature of pure and mixed states. Maybe you can help me out? 1) A pure state - superposition is a state that consists of different states at the same time. It's like having several waves, each one belonging to an Eigenstate of the...
  18. P

    Voltage and current phase shifting/Current without voltage?

    Hello, I've recently been learning about capacitance and inductance causing the current to lead or lag. But how can the current possibly maintain the same waveform? Shouldn't the zeros of voltage and current always align? How can there be current without voltage?
  19. V

    I Derivation of phase change parameter in dispersive medium

    Hi, I'm trying to evaluate the derivates of first, second and third order of the phase change parameter in a dispersive medium. In such medium the refractive index is a function of the wavelength. In my case it depends on the wavelength in vacuum. \begin{equation*} n(\lambda_0 )\end{equation*}...
  20. 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...
  21. 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?
  22. 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?
  23. D

    Phase speed of the wave

    Homework Statement transverse wave is traveling through a wire in a positive direction of the x-axes. Distance od the wire particles in the motion of the wave can be described as ##y(x,t)=53*10^{-6}sin(188t-3.14x)## Find the ratio of the phase wave speed and maximal speed of the wire particles...
  24. T

    Find TX turns ratio and 'class' questions?

    Hi, Just made a small thought experiment on the train, haven't really thought about it in depth. I was just wondering, if I created the above scenario (open circuit secondary and a voltmeter), would I get a voltage (assuming there is a difference in turns for primary and secondary)? Neglecting...
  25. J

    A Reducing standing waves with phase randomization

    Will constantly randomizing the phase of an audio signal, say a speaker in the corner of a square room, reduce standing waves (i.e. room modes) in the room? For example if you wanted to create a diffuse field in a small (i.e. no standing wave interference patterns) at low frequencies.
  26. P

    Efficacy of Balanced XLR Cables for Noise Reduction

    When attempting to find an answer to the "quality" of sound one attains from various audio cables, most of the research leads to the very subjective answers of audio/sound engineers. I was hoping to gain some insight from a physics/engineering perspective. I'm curious if an expensive or...
  27. T

    Rotational Inertia Gas vs Liquid

    I am conducting an experiment that rotates a sealed donut cylinder to investigate amongst other things the inertia of the contained fluid. Process I rotate the cylinder to a set speed (assuming that the viscosity of the internal fluid will end up rotating the fluid to solid body rotation)...
  28. LarryS

    A Is Phase Relevant for Uncharged Particles?

    Global phase invariance has been identified with the conservation of electric charge. Local phase invariance via the coupling of the wave function/field with the EM four-vector has been identified with charged particles interacting with the EM field. Am I correct in assuming that, except for...
  29. P

    EM Wave: Phase of the electric and magnetic waves?

    In a vacuum, the plane wave solutions to Maxwell's Equations are... E=E0*cos(wt-kr) B=B0*cos(wt-kr) ie they are in phase. (See for example ) I don't...
  30. G

    Origin of latent heat

    Hello, We often hear about latent heat of vaporisation for a liquid, which basically corresponds to the energy required to break the hydrogen inter-molecular bonds in the liquid phase to form the gas. I was wondering, what is the equivalent physical explanation for the latent heat of a...
  31. A

    Effect of Phase Lead Compensator on Phase and Gain margins

    Homework Statement I was just wondering what was the general effect on phase and gain margins when a phase lead compensator was is added to a system. Homework Equations The Attempt at a Solution
  32. R

    Phase Difference Help

    Homework Statement There is a spring with 2 masses with a combined mass of 0.69kg. The vertical oscillation has a frequency of 1.5Hz. The amplitude of the oscillation is 30mm. Now this spring is attached to a horizontal support rod that can be made to oscillate vertically. how do i work out...
  33. TheOfficialAB

    Crystal phase transition, Diffraction peak splitting problem

    Homework Statement [/B] Hi there! This is a question from a practice problem sheet I got from the lecturer of my Condensed Matter 1 course. Below are the normal vectors to the {111} and {112} lattice planes: Homework Equations [/B] Bragg Condition: \begin{equation} n \lambda = d \sin...
  34. S

    Phase Cell Elementary volume

    Hello, Am having this confusion that in Boltzmann approach to Statistical Mechanics, the phase space was divided into small phase cells whose magnitude was of the order of (h^f) but Boltzmann also made the assumption that the smallest phase cell must contain a large number of atoms. Doesn't this...
  35. onion3000

    Help with understanding modulation in AM, FM and PM radio

    I have a few questions about AM, FM and PM. 1. If FM (or PM) radio modifies the frequency of the signal, how is the signal picked up without having to change the frequency constantly? 2. If PM modulates phase, which modulates frequency, what is the difference between PM and FM? 3. Why is AM...
  36. GiantSheeps

    In what phase of matter do Neutrons/Protons/Electrons exist?

    In what phase of matter do individual Neutrons/Protons/Electrons exist? They are matter aren't they? So they must exist in some phase, right? Do they change phase? I'm very curious any information would be greatly appreciated. Thanks!
  37. DeldotB

    Derivation of "arcsin" phase shift formula

    Homework Statement Good Day, On an oscilloscope, when two incoming signals are out of phase, in an XY setting, an ellipse appears on the oscilloscope screen. The phase shift between the two incoming signals can be found by the formula: sin^{-1}((Y_{max})/(Y_{int})) where Y max is the...
  38. A

    Wave function for transverse waves on a rope

    Homework Statement Serway's Physics for Sciencetists and Engineers with Modern Physics, 9th Edition (current), Chapter 16, problem 19:[/B] (a) Write the expression for y as a function of x and t in SI units for a sinusoidal wave traveling along a rope in the negative x direction with the...
  39. R

    How to compute phase of the signal?

    Suppose you are given a phase spectrum or (/and) equation of the (main) signal only and you are said that the given (main) signal is formed of 3 other signals. Is it possible to compute phases of these three signals from the equation or (/ and) phase spectrum of the (main) signal? Also,what...
  40. VoteSaxon

    Van der Waals and boiling point

    Homework Statement The bulb of a constant volume gas thermometer is immersed in an ice/water/water vapour mixture at equilibrium and the recorded pressure is 0.400 atm. It is then immersed in a boiling liquid and the pressure is 0.844 atm. Sufficient gas is then removed from the bulb such that...
  41. T

    Quadrature Booster or Phase shifting TX

    Hi, Does anyone know about these? Specifically I'm trying to figure out changing the tap on the Delta effects the series voltage: source wiki: Any vector diagram or word explanations will help. Also, what size diameter coils must be used on the...
  42. R

    Physically what is phase of an Image?

    Hello everyone,I want to ask very basic question related to multidimentional signals like an image or a video signal. Physically what is phase of an Image? Also what is its physical significance of phase compared to magnitude of an image?
  43. T

    Two moons in tidal lock orbit: phases, tides, axial tilt?

    Consider the following; We have Earth with two moons in orbit (discounting the existence of our own moon for the sake of this hypothetical scenario). One moon is the size and mass of Pluto, orbiting around 70,000km from Earth. The other is the size and mass of Pluto's moon, Charon, orbiting...
  44. C

    Vout = (a+jb)Vin, what do A and B stand for?

    Homework Statement I was given a graph with two waves on it, the input and output wave. I found the frequency of the waves, change in magnitude and change in phase. The last question asks me to write the transformation from input to output as a phasor and he gave the relevant equation below...
  45. J

    How do you get 2 wires on AC out of phase by 180 degrees?

  46. F

    Waves Find the phase constant from the graph.

    Homework Statement Find the phase constant Homework Equations x(t) = Acos(wt + Φ) x(t) = Asin(wt + Φ) w = 2pi/T The Attempt at a Solution I see A = 20cm. T = 4s. f = 1/4 = 0.25Hz. w = 2pi/4 = 1.57Hz. 10 = 20cosΦ 0.5 = cosΦ Φ = π/3, 5.24?
  47. N

    Question about electricity towers and poles

    I have several questions about poles and towers. a. Does all of transmission towers carries three-phase powers? Is there no transmission towers designated for single-phase? b. Does all towers are for transmission purposes only? Is there any towers in the world used for distribution instead of...
  48. S

    Electric & Magnetic Fields in EM Waves: Explained

    Why are electric and magnetic fields in an electromagnetic wave in phase? Can somebody please explain that?
  49. M

    Phase Difference

    There are two waves y1=a. sin(ω.t) & y2=a. sin(ω.t + φ) My question is what is the phase difference of these two waves? Is it "φ" or "φ/ω"?
  50. B

    Energy in phase transitions

    Sorry for such a simple question but where do we model the energy going during phase transitions? If I had a mercury thermometer in a pot of water, and I had a 200 degree Celsius heat reservoir in contact with the water, I would see the water temp hold steady during the phase transition...