Phase Definition and 1000 Threads

I am studying induction motors and i have equation for instantaneous value of current flowing in each phases.(please check to image below).I can see that its it the form Im.cosωt But isn't it supposed to be Im.sinωt ?because that's how we find all instantaneous parameters like voltage and...

Hello. In the following(p.2): https://michaelberryphysics.files.wordpress.com/2013/07/berry187.pdf Berry uses parallel transport on a sphere to showcase the (an)holonomy angle of a vector when it is parallel transported over a closed loop on the sphere. A clearer illustration of this can be...

Homework Statement I have included the problems attached below. I have looked at a recent post and the equations made sense to me but I am very new to 3 phase systems basically know only what I have learned from trying to answer my questions. i feel my attempt is wrong from what I have seen...

Hello everybody. I am trying to understand better what happens at a liquid-gas phase transition for the Van Der Waals model. From what I have understood, from the Van Der Waals model we are able to plot the curve P(V) and to calculate the free energy F. Here are such curves : Then, we...

<< Mentor Note -- thread moved from the technical forums, so no Homework Template is shown >> [/color] I'm studying controlled rectifiers and for full wave bridge rectifiers the notes(that I'm studying from says) It says that the average load current is Id / 2 I don't understand how. Why...

Like we write "R+jX" where jX is considered to be imaginary term and it said to have 90 degree phase shift.

Greg Bernhardt submitted a new PF Insights post Mathematical Quantum Field Theory - Reduced Phase Space Continue reading the Original PF Insights Post.

I'm trying to measure correlation between two RF noise sources and as usual trying to do it on the cheep. I've purchased 2 SDRPlay RSP2pro radios. These operate from 500kHz or so to 2 GHz with sampling rates from 2 to 10 MHz. Not bad for $200 and they work well as radios. The RSP2s have in and...

Hello, My question is about the calculation of phase shifts δl in scattering theory. Some article mention that we can obtain phase shifts by numerically solving the radial Schrodinger equation but I'm not sure how to do it. Do you know how to proceed? is there any code (python, c ++, ...)...

Hey everyone, I'm trying to measure the stray capacitance in a circuit comprised of an rf signal generator, an oscilloscope, a coaxial cable (short-circuited) and some capacitors. I measured the resonant frequencies of the coaxil cable for varying values of capacity (0pF to 850pF) between 4MHz...

Hey all, I was reading Efficient Linear Optics Quantum Computation by Knill, Laflamme, and Milburn, when I came across their expression for the Hamiltonian for a phase shifter, given as ##\textbf{n}^{(\ell)} = \textbf{a}^{(\ell)\dagger} \textbf{a}^{(\ell)}##, where ##\ell## indicates the mode...

Hi, I start at 100 MHz have 10 carrier frequencies all starting in phase at t=0 and the carrier frequencies have 25 kHz spacing. So my frequency range is 100-100.25 MHz, with 10 single frequencies equally spaced in this range. They are therefore all different frequencies, spaced 25khz apart...

Hi, I start at 100 MHz have 10 carrier frequencies all starting in phase at t=0 and the carrier frequencies have 25 kHz spacing. So my frequency range is 100-100.25 MHz, with 10 single frequencies equally spaced in this range. They come in phase every 4x10-5 seconds. The equation Frequency = 1...

Greg Bernhardt submitted a new PF Insights post Mathematical Quantum Field Theory - Phase Space Continue reading the Original PF Insights Post.

Homework Statement Calculate the geometric phase change when the infinite square well expands adiabatically from width w1 to w2.Homework Equations Geometric phase: \gamma_n(t) = i \int_{R_i}^{R_f} \Bigg< \psi_n \Bigg | \frac{\partial \psi_n}{\partial R} \Bigg > dR Infinite square well wave...

Hi guys, I am working on a project that involves measuring the phase angle between two sinusoidal voltages. The circuit under examination is an RL type (the resistor was in series with the inductor), where the phase of voltage across the inductor is measured relative to the voltage input of the...

Hello, All substances that are either in the liquid or solid state have a small vapor pressure which implies that they are always slowly (solids especially) evaporating and turning into a gas (vapor). The phase diagrams of water and carbon dioxide indicate only states (P , V) of pressure and...

Question Consider a heating system with strongly inductive characteristic and with an electronic control of temperature performed by varying the firing angle of a single-phase controlled bridge. a) Determine the value of resistance to to ensure a maximum power of 7500W if this system is powered...

Could somebody show me how to derive this equation? How can I get right side from left. Step by step, thanks...

Homework Statement I need to first find phase current in the load and line current from the supply Homework EquationsThe Attempt at a Solution I thought it would be easier to work with a star because then the Ztl would be in series with it... I am not sure how to find the current but my best...

Homework Statement I am studying for an exam and I never know if I am finding line current / voltage or phase current / voltage. How can I tell? I guess I am confused on what "phase" and "line" represent. For example: If I do the voltage divided by the impedance, then this gives me phase...

In state space, the coordinates are the state variables of a system.So,each point in state space represents a specific value of state variables.Thus,state space representation represents the changes in a dynamical system. The state variables are the minimum number of variables which uniquely...

Homework Statement Two sinusoidal voltages with amplitude 15Volts and frequency 2,771Hz are separated in time by 68% of a period. What is the phase shift in degrees between the two signals?Homework Equations y= Asin(omega)(x-h) The Attempt at a Solution I know my A is 15 and I'm pretty sure...

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...

Hi Problem: Three loads are connected in parallel across a 12.47 kV three-phase supply. Load 1: Inductive load, 60 kW and 660 kvar. Load 2: Capacitive load, 240 kW at 0.8 power factor. Load 3: Resistive load of 60 kW. (a) Find the total complex power, power factor, and the supply current. (b) A...

Homework Statement Homework EquationsThe Attempt at a Solution This is the Solution. I am having trouble understanding parts of it. The first part I don't get is why the e^i... goes with the -z. Did my professor just choose one at random, or is there a specific reason? The second part...

Homework Statement I am trying to understand a solution to a problem. I may not need to post the entire question, I just need to know if ##-i = e^{\frac{-i*pi}{2}}## Homework EquationsThe Attempt at a Solution the reason for this question is that one step of the problem has a quantity...

Hi, i would like to know how can i plot a three dimentionnal phase space (mathematica), for this kind of differential equations: x'= (z^2(x-4y+z)+y^2(x+z)+z(x*y-x^2))/(z^2+x^2-2) y'=y(y-3)+z(4y-z)+3(1-x^2)-2(y-3z)(z^2(x-4y+z)+y^2(x+z)+z(x*y-x^2))/x(z^2+x^2-2)...

In Quantum Mechanics Concepts and Applications by Zettili the following formulas are used for phase and group velocities. {\rm{ }}{v_{ph}} = \frac{w}{k} = \frac{{E\left( p \right)}}{{p}}{\rm{ }}\\ {\rm{ }}{v_g} = \frac{{dw}}{{dk}}{\rm{ = }}\frac{{dE\left( p \right)}}{{dp}}{\rm{ }} In...

It is reported that TiO2 thin surface amorphous layer left after acid-etching with hot HCl-H2SO4 solution slowly changes from the original flat surface to a layer rich in nano-scale features (granules attached to the surface) of 20 ~ 30 nm in size. You can see these nano-features in the picture...

Homework Statement Homework Equations This is the way to solve when magnetic field B is arbitrary direction one. The Attempt at a Solution I got a eigenvalue of this Hamiltonian and eigenstates. but i have no idea how to set a coordinate to value the gradient

What is a symplectic manifold or symplectic geometry? (In intuitive terms please) I have a vague understanding that it involves some metric that assigns an area to a position and conjugate momentum that happens to be preserved. What is 'special' about Hamilton's formulation that makes it more...

I have a problem with the phase of an electric field as it is reflected by and transmitted through a dielectric interface. At the boundary between the two media, all waves must exist simultaneously and the tangential component must be equal on both sides of the interface, right? Therefore for...

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?

Could we calculate (linear) electric polarizability from Berry phase?

I am looking for a graduate level textbook that would sufficiently describe the two phase flow characteristics during flow boiling. What textbook could I use to explore this topic? Is a graduate level forced convection going to cover two phase flow?

My question is :what is the role of neutral conductor in the 230v European single-phase system .My assumption how it works that a neutral conductor serves to close the circuit between phases and to carry the imbalance current between different phases If all the phases are balanced then the...

Well, I have to show mathematically that T remains unchanged in phase change. I know it comes from sperimental evidences, but my professor asked to show it with "numbers". So I thought to go like this: (dH_l)/dt ≈ (dm)/dt) h_v + Q Energy balance for system (let's say it is liquid and changes...

Homework Statement Homework Equations Power Triangle and 3-phase equations (listed in my solutions) The Attempt at a Solution Here are the instructor solutions: The instructor solutions just go straight into using equations, but I like to use the power triangle because it is more...

Hello, I have heard that one of most acceptable theory (or hypothesis) describing the inflation phase of universe is that energy to this stage is drawn from phase transition when strong interaction is separated from "preinteraction" (when all interactions were undistinguishable) Do you agree...

I have information about temperature, pressure, normal and shear stresses, viscosity, conductivity, density, heat capacity and adiabatic heating for a particular area of mantle in the form of 2D matrices. I want to show phase relation for this region of mantle. Is there an equation (group of...

When a refrigerant crosses a heat exchanger device or has some heat added into it, like condenser/evaporator or boiler/cooling tower, does the phase always change? If that's so, why? Or do we need to check if the temperature is above or under the boiling point?

Homework Statement An electromagnetic wave with the frequency f = 1.4 GHz is propagating in the z-direction from vacuum in a plasma with the magnetic field B_0 = 0.1T z^. The plasma density is 1.0*10^17 particles/m^3. The wave is the separated into a R- and L-wave in the plasma. Homework...

How exist voltage between hot and ground? How we are connected to ground through wood floor, building when we use tester screwdriver?

Hi. I'm reading an article about QCD phase diagram. https://arxiv.org/abs/1005.4814. I want to derive eq(20), but I don't know how. Does anyone know how to derive this?

Hello everyone, I'm actually working on developping a phase shift sensor using one phase modulated signal, i know that the title is confusing beaucause the phase shift measurement need two signals , I'm trying to do this with the zero crossing method so if I could found the timestamps of the...

The rotor and stator flux speed are stationary with respect to each other in 3 phase induction motor. What will happen if there is relative speed between them? How these two fluxes interact with each other to develop a torque?

Hi, I'm recently reading "Particle Physics in the LHC Era" and there is a part about the phase space factor that confuses me. When giving the Lorentz invariant phase space, they wrote: d3p / 2E = θ(E) δ(p2 - m2) d4p This is very confusing as it equates a three dimensional differential to a...

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...

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?