Phase Definition and 1000 Threads

So I noticed we can define entropy in two very different ways: 1) quantum mechanically S = -k Tr(\hat{\rho}\ln{(\hat{\rho})}) 2) classically S = -k \int \rho \ln{(\rho)} d\Gamma where Tr is the trace and d\Gamma = \frac{1}{h^{3N}N!}\prod_{i}^{N} d^{3N}q_{i}d^{3N}p_{i} is the phase...

You have a yellow lamp in your spaceship. Now you accelerate your spaceship significantly. Then you stop accelerating. Does the lamp still have the same color? I would think it should, but I reckon differently as follows: Consider the situation from an outside observers point of view, resting...

I'm confused regarding the phase diagrams of binary systems. Let's suppose we mix 2 liquids, A and B at a given pressure P that won't change during the whole experiment. I raise the temperature until I observe that some of the mix of liquids vaporizes. What boggles me is that it seems I can...

I am stuck with another one -- Assume that f(x) has the following graph: (for graph please see the attachment) Consider the (1-dimensional) ODE: X’ = f(x): (a) Find all the xed points, and study their stability. (b) Draw the phase portrait of the system, as well as the graphs of the...

Hi guys! So I've just recently started learning about phase relationships for inductors and capacitors in an AC circuit. But a few things keep bugging me: Say we have a RL circuit (a resistor + inductor + voltage source all in SERIES), and we we're asked to draw a phasor diagram for the...

Hi. I am trying to understand some features related to the order of a phase transition. It is known that there are finite size effects in a finite system. The finite size scaling theory provides relations between some quantities with the length of the system L. At second order phase...

Hello everyone, I'm designing an experiment which utilizes a single agent in different phases (liquid, gas, and plasma). The apparatus needs to be able to ionize the gas into a plasma (with +/ - 1 or more electrons). I'm trying to keep energy consumption at a minimum, so current phase...

I was thinking of a substance I could use to describe particle arrangement in solid/liquid/gas phases to school kids, and after realising water would be bad to use (since the liquid is denser than solid), I thought of using metal elements since they can exist in all phases. Basically the...

I Still don't understand why the group velocity has to be less than c but phase velocity not. Can you explain me this? Thank you :cry:

To what extent do phase space trajectories describe a system? I often see classical systems being identified with (trajectories in) phase space, from which I get the impression these trajectories are supposed to completely specify a system. However, if you take for example the trajectory...

Homework Statement Reference the Cu-Zr phase diagram. If you make the alloy CuZr and heat it to 300°C, what percentage of the material will be Cu10Zr7 and what percentage of the material will be CuZr2? Homework Equations Phase diagram attached. The Attempt at a Solution I used the lever...

Homework Statement The potential difference across a circuit is given by the complex number V=40+j35volts and the current is given by the complex number I=6+j3 amps a) sketch the appropriate phasors on an Argand diagram. b) Find the phase difference between the phasors for voltage V and...

Hello, For our final lab we will be given a box with three wires, the neuter is missing. In the box there is a Y or delta configuration and we can use everything to find out if it is a Y or a delta configuration. So, voltmeters or watt meters, or even something like tin foil. Can someone...

Homework Statement What is the phase velocity of light in glass if n=1.5 at λ=500nm Homework Equations n=c/vp =λ0/λ The Attempt at a Solution 1.5 = (3x10^8) / vp vp = (3x10^8)/1.5 I'm not entirely sure if the equation I have used is the correct one. It does not use the...

Homework Statement (i) What is the phase velocity of EM radiation in free space? (ii) What is its group velocity? Homework Equations The Attempt at a Solution Using the definition as per this page: http://physicsdaily.com/physics/Phase_velocity (i) Vp = (C^2)/Vg (ii)...

Hi, In the study of dynamical systems, phase portraits play an important role. However, in almost all related text, I only see some standard examples like prey-predator, pendulum etc. I have a rather unclear thought in my head regarding the role of real/imaginary eigenvalues in the system...

Homework Statement Light with wavelength 540 nm is split into two beams that travel along two paths. The difference between the path lengths is 3600 nm. What is the effective phase difference when the light recombines? Homework Equations \phi = (2pi/λ)*ΔL The Attempt at a Solution...

Homework Statement Refer to the attached binary phase diagram. Substance A has a melting point of 600 °C and B has a melting point of 1200 °C. A mixture of 70 weight percent B and 30 weight percent A is held at 950 °C for a long time - long enough to reach equilibrium. a) Determine the weight...

I am trying to learn how to use phase transformation diagrams and I don't get it. Any help from someone who knows about this would be greatly appreciated (I have a final tuesday) An example problem is below with the picture attached. I have to be able to find what the microstructure is after...

Hello everyone, Thanks in advance for any wisdom you can offer regarding this matter, I just joined physicsforums.com and am now wondering why I haven't been a member all along... My crudentials: I'm an electrician that went part way through college for electrical engineering, however Its...

Hi, if a load is given in MVA and I work out the Real and reactive power, is the equivalent complex impedance per phase the values of real and reactive power divided by three in the following form: Z (per phase) = Real power/3 + j Reactive power/3 Im not sure how to work out whether the...

1. Hey, the question I believe should be fairly simple to solve but it's been a while since I've looked over such content. There are two light waves that enter a crytstal at the same time, one linearly polarised parallel to the optic axis and one perpendicular to the optic axis, they have...

If I understand well like in kinematics where we could have eq of motion ##x=x(t)##, ##y=y(t)## and we get eq of trajectory with elimination of time. In dynamics we have ##x=x(t)##, ##p=p(t)## and with elimination of time we get eq of phase trajectory. Am I right?

Why nλ= 2∏r? this is the explanation from website , Now, one complete orbit has the same length as the circumference of the circle that the orbit traces out, so is given by 2πr. This distance must be equal to an integral number of wavelengths. (If it were not, the wave traced out by the...

Homework Statement An Unbalanced 3-phase star connected load has the details as below. Line Voltage=400V Voltage R-N = 230V 0° Voltage B-N = 230V +120° Voltage W-N= 230V -120° Impedance R-N = 100+J36 Impedance B-N = 102+J0 Impedance W-N = 50+J0 A.) Determine the neutral...

Hey all, I am having trouble with this problem: A sampled sinusoidal signal having a normalized frequency of 0.30π is sent through an FIR filter. The filter impulse response is, h[n] = 1/3δ[n] + 1/3δ[n-1] + 1/3δ[n-2] From this I must find out by what factor the input signal is...

Hi, I am trying to implement phase dispersion in a retarded time frame. c_{phase}(ω) = c_{0} + c'(ω) where c'(ω) is a small deviation from the reference phase speed c_{0}. In the frequency domain, the propagation term appears as an exponent: e^{-(\alpha + iω/c_{phase}(ω))z} where z is...

Homework Statement Saturated liquid CO2 is at T= 293 K and P=5.72*10^6 Pa and undergoes throttling to P=1.01*10^5. The resulting solid and vapor mixture is at T = 195 K. What fraction of the carbon dioxide is vaporized? (The enthalpy of the saturated liquid in the initial state is 24,200...

Homework Statement A mass is attached to a spring on a frictionless horizontal surface. The mass is pulled to stretch the spring by 0.1 m, & then gently released. A short time later, as the mass passes through the equilibrium position, its speed is 1 m/s. Part a) What is the speed of...

Homework Statement Homework Equations The Attempt at a Solution Is my initial assumption wrong?

Homework Statement An observer stands 3 m from speaker A and 5 m from speaker B. Both speakers, oscillating in phase, produce waves with a frequency of 250 Hz. The speed of sound in air is 340 m/s. What is the phase difference between the waves from A and B at the observer's location...

hi all, its been hours that i could not find a decent answer for a 'simple' Q: during a phase change (say, boiling) the temp' doesn't change, as we all know. we also know that the temp' is a measure of the system kinetic energy (KE). im interested to know how the average KE AND its...

My question is: With a controller gain that meets the condition on the ramp set point, what is the largest achievable phase margin? I have no idea what the solution is saying! Does anyone know what this means exactly??

Here's the question: 1. In classical mechanics, we know that the evolution of a system, that is the trajectories of the particles and objects, does not depend on where we chose the xero-point of the potential energy. Here we analyse what happens in quantum mechanics. Assume that you add a...

Homework Statement Two flat slides of glass are separated at one edge by a thin wire, as shown below. The top surface of the upper slide and the bottom surface of the lower slide have special coatings on them so that they reflect no light. The system is illuminated with light of wavelength...

I'm studying phase transitions in statistical mechanics, and I'm curious to know more about how the partition function becomes zero. I've read a bit about the Lee Yang theorem, but haven't found a good description of the whole program. Does anyone have a good paper on the subject? (Other than...

Homework Statement A beam of light of wavelength 606 nm passes through two slabs of material of identical thickness d= 1.40 micrometers, as shown in the figure. The slabs have different indices of refraction: n1= 1.51 and n2= 1.68. What is the phase difference (in radians, do not enter units)...

Homework Statement Hi, I've been having trouble setting up an oscilloscope, with a AC voltage supply, to a breadbox, with a "black box" in the circuit. the black box is just a set of 3 pairs of terminals, each a "unknown component" such as a diode, capacitor, resistor, etc. Basically I need...

I use transfer matrix method. I try to plot the phase Φ(ω) versus frequency ω graph in the vicinity of a band gap. The transmission coefficient t(ω) is t(ω) = |t(ω)|*exp(i*Φ(ω)) from which I get the transmission phase Φ(ω) = atan(t_imaginary(ω)/t_real(ω)). Since I assume that -pi/2 ≦ Φ ≦...

The phase velocity of ocean waves is (gλ/2∏)1/2,where g is the acceleration of gravity.Find the group velocity of ocean waves. Relevant equations: λ=h/γmv phase velocity= c2/v(velocity of particle) group velocity=v (velocity of particle). thnxx in advance

When a substance undergoes a phase change from a solid to a liquid the substance can absorb heat energy without undergoing a temperature change. But I also read that when a substance melts, the atoms absorb energy and thereby vibrate faster, overcoming the intermolecular forces. Temperature is...

Imagine that an excited hydrogen atom in the symmetric 2s state emits a photon. We use a birefringent crystal to split the photon into vertical and horizontal components. Is the phase relation between these components random or is it the same for every photon emitted by a similarly excited...

Homework Statement Three load each having a resistance of 16 ohms and an inductive reactance of 12 ohms are wye connected to a 240V three phase supply. Determine: a) the impedance per phase b) the current per phase c) the kVA total d) the Power Factor e) the kW total Homework...

Homework Statement Hi, I have a test and need to prepare with the following questions. Unfortunately, we don't have any material to read in order to prepare. I was hoping that somebody could please help me answer at least some of these questions, or provide me with a source where I can find...

3 PHASE INDUCTION MOTOR A 15 hp/230V, three phase induction motor has a full load current of 42A per terminal. 15HP= 11kW find: a) Full load kVA input b) If the full load power factor is lagging 0.85, what is the kW input. My question: How do I know whether its connected Wye or Delta?a) kVA=...

Is there any relationship between phase space and entropy? regarding to decay of particles

I am doing project on open loop v/f control of three phase induction motor. How to decide the frequency and amplitude of triangular wave(carrier wave) for sinusoidal PWM ?

Homework Statement A man is sitting between two speakers, 5 meters from the first and 6.5 meters away from the second. Speaker 1~~~~~~(6.5m) ~~~~~~ Man ~~~~ (5m) ~~~~ Speaker 2 They both create sound waves in phase. What's the lowest frequency for which the man hears both sounds in phase...

So for the phase velocity of a massive particle we have Vph = Vg/2 for non-relativistic case Vph = c^2/Vg for the relativistic case Vg is the group velocity or particle velocity But there seems to be a contradiction in that for the non-relativistic case the phase velocity is...

i am looking for the amplitude ratio and phase shift of this graph? could someone explain me how to obtain these results from this type of graph? thank you