Phase Definition and 1000 Threads

Hi Sir, I have seen in many IEEE magazines that, a six phase induction motor is having two 3 phase windings spatially separated by an angle of 30 degrees electrical. I have attached the 6 phase induction motor diagram. But I am not able to understand how the motor operates i.e. how the rotor...

Hi, According to what I understood, when a terminal is connected to a line, it causes electrons to flow in one direction. And so for a single phase transmission line in parallel if connected to supply, then in one side electrons will be flowing in one direction and the same electrons will be...

Greetings, I've been searching online without success for information related to the process (name?) Of utilizing the repusive force between negatively ionized particles to facilitate a change of phase from liquid to plasma. I would like to be able to take a substance in liquid form inside a...

Why must the charged particle that leads to Cherenkov radiation travel faster than the phase velocity of light not the group velocity of light? One of the sides of the triangle that is used to define cosθ is v=c/n i.e. the phase velocity. I don't see why it's one rather than the other. Thanks!

I am still trying to solve this but I first, I need someone to explain to me about the sum of the currents, which I don't understand. The phasor of current I1 is 2+3j[A], and the phasor of current I2 is 1[A]. 1) Find the value of impedance Z. 2) Let the phase difference (arg(I3/I4)) between...

At resonance (## \omega_0^2= 1/LC##) in an LCR-Circuit the phase angle given by \theta=\tan^{-1}\left( \frac{\omega L - 1/\omega C}{R} \right) obviously is zero. And still there are other phases to deal with. This I don't understand. Let me elaborate. For example when calculating the amount...

The Berry connection and the Berry phase should be related. Now for a topological insulator (TI) (or to be more precise, for a quantum spin hall state, but I think the Chern parities are calculated in the same fashion for a 3D TI). I can follow the argument up to defining the Chern parity $\nu$...

Good morning, Before all, I also posted a question to maths forum, but I am convienced that this is the forum I was more like looking for. Firstly, hello to this forum, secondly I want to apologize if this is not a place I would like to post a question like that, maybe in another thread ?; )...

Hi, I'm Teemu from Finland, and I'm just getting my master's degree in physics completed (only one course in electronics left). This is my first post in Physicsforums. I was thinking about a problem in statistical mechanics. As you all know, if we have a one- particle system where the...

Hi PF! I just took a test for my class and there is one problem I can't get my mind off of. I'm not necessarily looking for the correct solution here, just if my thinking was correct. It went more or less like this: there is 40g of ice at 0 degrees C in 200g of water in an aluminum calorimeter...

On a (T,P) phase diagram, what is meant by the pressure at each phase for the substance? Chemically speaking we are only usually dealing with "gaseous" pressure (i.e. that exerted by the gases), but only when the substance is in (one of the phases in) the gaseous state or supercritical fluid...

I just started to use a lock-in amplifier, and I am trying to following the procedures by adjusting zero phase. But my input phase changes with time and sensitivity, and I couldn't lock in onto it. The question is, is this normal that phase changes all the time during the experiment or if there...

Say ##V_{out}=4e^{j\frac {\pi}{6}}##, what is this mean? It is a scalar voltage. Does this means: 4e^{j\frac {\pi}{6}}=4\left(\cos \frac {\pi}{6}+j\sin \frac {\pi}{6}\right) = 4(0.866+j0.5) = 3.4641+j2=4\angle 30^o What is the phase shift means, reference to input? Thanks

Hi there, In my course solid state physics, there is a part about the Lorentz oscillator. At a certain part, this is written: "X(t) = X_0sin(-ωt+α) This changes into: X(t) = X_0 exp(-iωt) by choosing X_0 as a complex number and putting the phase factor into the complex amplitude."...

Hi. Today I sat my final first year Modern Physics exam. It went very well, however I got stuck in one question. It asked (i) to prove the following relation for the matter wave \omega^{2}=k^{2}c^{2}+m^{2}c^{4}/\hbar^{2} and (ii) to obtain the group velocity and phase velocity of a matter wave...

On a phase diagram, the lines are "lines of equilibrium", i.e. at any point on these lines of equilibrium there is an established equilibrium between the two phases on either side of the line. The equilibrium constant is a function of temperature and pressure, and the various other thermodynamic...

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...

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...

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...

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...

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