Phase Definition and 1000 Threads

I am trying to understand the basics of bldc motor. My question is if i am driving the 3 phase motor with sinusoidal waveform. The magnetic field is produced for each phase or it will add together to generate net magnetic field? How to get the net magnetic field.

Numerically, speed of wave propagation(defined as wave velocity) = ω/k = phase velocity But, conceptually is there any difference between phase velocity and wave velocity?

and Homework Statement Ok, so I am doing As physics at the moment and have been left confused by stationary waves. I have read that between adjacent nodes/ even numbers the phase difference is always 0 and between numbers of does it is pi radians. So in the attatched image why is my textbook...

In a coherent state defined by |\alpha\rangle = \exp{\left(-\frac{|\alpha|^2}{2}\right)}\exp{\left(\alpha \hat{a}^\dagger\right)} |0\rangle there is a definite phase associated with the state by \alpha = |\alpha| \exp{\left(i\theta\right)} where the number operator and phase operator are...

Q1: So I'm trying to extract the electrical properties of a single phase induction motor. First off, how am I supposed to measure the phase difference between the start and run windings? I have L and R of start and run windings too! Q2: I have a torque vs slip curve up until 130% of rated load...

How would you justify the above question? Please elaborate in detail with diagrams (if applicable). It will be really helpful. Thank you.

Hello, I have been going over the above topic and have a question about the neutral point of a balanced wye configuration. Would the line to line voltage remain constant? I am trying to picture two sine waves 120° apart and it's making me think the Va would be reducing as Vb was increasing at...

Homework Statement Given the transfer function: Find the phase relationship between the input and output voltage at high frequencies Homework Equations NA The Attempt at a Solution My approach was to find the phase of the transfer function, which I got to be: I assumed that "very high...

Homework Statement An inductor (Xl = 40.2 ohm) is connected in series with a resistance (30 ohm) and and an AC source ( 10V , 80Hz) and the current flows in this circuit is 0.2 amp. How could you reduce the phase difference between current and voltage to zero without changing the value of...

Homework Statement The flux density in a single phase core type symmetric(length=breadth=height) transformer is B and flux is Φ. Can we find out the volume of core of transformer if the height of limb is h? Homework Equations Φ = B * Cross sectional area The Attempt at a Solution Can we say...

Homework Statement State the phase relationship between x and y x and z (shown in photo) The Attempt at a Solution I got the phase difference between x and y to be 135 degrees and then between x and z to be 45 degrees. However the mark scheme gives the answers 180 degrees and 0 degrees. Please...

Draw a single light ray through a spiral phase plate, anywhere but the middle of the plate, with the incoming ray being parallel to the axis of the spiral phase plate. On passing through the plate the ray is no longer parallel to the axis of the phase plate? Does the change in direction account...

Hello everyone. So I have a test coming up and I am struggling with the concept of figure out what the initial phase or angle of a transfer function is. For instance, consider the following transfer function: L(s) = 4/s(.4s+1)(s+2) So the initial angle for L(s) is -90 degrees. Is there a...

"At pressures above the critical pressure, there is not a distinct phase change process. Instead, the specific volume of the substance continually increases, and at all times there is only one phase present." What does "distinct phase change" mean here? First to understand this I should...

In a beam splitter with one vacuum input, the output looks like ##\frac{1}{\sqrt 2}(|1_A\rangle +i|0_B \rangle)\frac{1}{\sqrt 2}(-i|1_A\rangle +|0_B \rangle)##. If there is some further processing, the vacuum ##i|0_B\rangle##, along with the i , could end up multiplied with some non-vacuum term...

Homework Statement If a metal is adhered to a surface of another metal, let's say copper is plated onto aluminum, how can the elastic modulus of copper can be extracted given only the data of the thickness of the copper and aluminum, the young's modulus of the combined metal and the modulus of...

How would this operator be implemented physically if we had a quantum computer? In Grover's algorithm this magical operator is often called "phase inversion". Here is the operator from wiki: https://wikimedia.org/api/rest_v1/media/math/render/svg/07fb23bffa787430b084971c6a108a8f6ff6c2b3 It’s...

Homework Statement Homework Equations ##V = ZI## ##Z_R = R## ##Z_C = -\frac{j}{\omega C}## ##Z = \sqrt{R^2 + (\frac{1}{\omega C})^2}## ##P_{av} = \frac{1}{2}V_m I_m cos(\phi)## ##\phi = arctan(\frac{-1/\omega C}{R})## ##\Delta \phi = \phi _1 -\phi _2## The Attempt at a Solution I've found...

Hi. I'm trying to prove that [\Omega] = \int dq \int dp \, \rho_{w}(q,p)\,\Omega_{w}(q,p) where \rho_{w}(q,p) = \frac{1}{2\pi\hbar} \int dy \, \langle q-\frac{y}{2}|\rho|q+\frac{y}{2}\rangle\,\exp(i\frac{py}{\hbar}) is the Wigner function, being \rho a density matrix. On the other hand...

Homework Statement Consider a glass plate of refraction index n and thickness ## \Delta x ## placed between a point monochromatic source S and an observer O, as in picture. (a) Prove that, if absorption from the plate is neglegible, then the effect on the wave received by O is the add of a...

Given a massive particle traveling freely. Also assume that it is in a momentum eigenstate - a pure unmodulated sine wave in position space. In non-relativistic quantum mechanics, the phase velocity for that particle would be greater than the velocity of light. Does the phase velocity for...

I always had this doubt,but i guess i never asked someone. What's the main difference between the Classical phase space, and the two dimensional Hilbert Space ?

I have some trouble fully understanding the PLL block diagram shown below in the figure. The PLL circuit is used to generate currents (i alpha and i beta) which are in phase with the positive fundamental sequence of the voltage. I am using the book "Instantaneous Power Theory and Applications...

Homework Statement Two sinusoidal waves in a string are defined by the wave functions y1 = 2.00 sin (20.0x – 32.0t) y2 = 2.00 sin (25.0x – 40.0t) where x, y1, and y2 are in centimeters and t is in seconds. (a) What is the phase differencebetween these two waves at the point x = 5.00 cm at t...

What will be the graph of v=Vmsin(wt+theta) and v= Vmsin(wt-theta) and why?:oldconfused:

What happens to one of the components when it is at VERY low concentration in a two component alloy? My problem: Uranium decays to thorium. The thorium isotopes it decays to typically have pretty short half lives. During casting, it is well known that thorium fractionates to the slag, crucible...

I am investigating the nucleation on solid surface during liquid-liquid phase separation, I know the free energy change is and I don't know if it is correct to get Can someone calculate it to have a check?

Homework Statement A mass/spring system is set in motion. Find the phase constant with the given information. Given: k = 8 N/m (spring constant) m = 0.1 kg (mass attached to string) x0 = -0.12 m (position at t = 0) v0 = 0.9 (velocity at t = 0) Homework Equations x(t) = xmcos(ωt + Φ) v(t) =...

In 2D, if we define exchange statistics in terms of the phase change of the wavefunction of two identical particles when there are exchanged via adiabatic transport (https://arxiv.org/abs/1610.09260), we would discover that this phase can be arbitrary due to the topology of relative...

How can we calculate the rotation without seeing change of phase of object like in case of moon,we see the same phase of moon but how it can be rotating. So rotation without change of phase is possible if yes or no than how and why ?.

Hi, would it be possible to explain to me how does wave length, phase difference and path difference all link as I'm struggling with calculations involving these three things.

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*}...

It occurs to me that I've probably been confusing "phase" in a number of contexts. In particular: 1) If we write a photon's polarization as \psi = |x\rangle + e^{i\theta}|y\rangle, then we can call \theta a "phase." 2) When a photon bounces off a mirror, it picks up a relative phase of i. If I...

Hi, I recently started studying materials science and I am looking at a particular alloy of Copper Zirconium. I have identified a B1 phase and they call it a CuZr phase, which I 'm finding rather confusing. Initially I thought that CuZr meant that each unit cell in the lattice was composed of...

<Moderator's note: Thread split off from https://www.physicsforums.com/threads/what-happens-if-hot-wire-touches-earth-ground.800587/page-4#post-5704259> Why can a phase be grounded without blowing up such as in a star configuration ?No one has answered this sufficiently or simply.

What is the purpose of the shim inductor and how exactly does it function in PSFB topology? I noticed that I had dramatically improved efficiency when I added a shim inductor to my circuit, not too sure how or why this works though.

【Mod Note: moved from technical forum, so homework template is missing】 In a parallel circuit, one branch contains two equal resistors of resistance ##R_1## connected in series. The other branch contains a resistor of resistance ##R_1## in series with an inductor of variable inductance ##L##...

Somehow I am worried it is a can of worms, but I will still try. This started with a student confused with statements describing critical temperature for the gas/liquid equilibrium. Some books and sources state it is the highest temperature AT which it is possible to liquefy the gas just by...

Why phase difference of EM wave is changed 180 degrees reflected from denser medium? I will be glad if u give me the actual reason [emoji4]

Homework Statement A closed loop control system has three components, Controller, Process, and Measuring System. Each has it's own gain and phase angle. I understand how to find the total of the gain but I'm unsure as to how to find the total phase angle? Homework Equations Total Gain=...

Hello, after I read in an exercise that the pressure inside of a spherical water drop is different than the pressure outside, I'm a little bit confused. Which is the pressure used in Gibb's phase rule and why don't the pressure change the form of the water drop?

Homework Statement (a) A transmission line has a length, ##l##, of 0.4λ. Determine the phase change, ##\beta l##, that occurs down the line. Homework Equations ##\beta=\frac{\omega}{f\lambda}## or ##\beta=\frac{2\pi}{\lambda}## The Attempt at a Solution This question was posted a couple of...

Homework Statement Let \begin{equation*} f(t) = 2 + \cos\left( 3t - \frac{\pi}{6} \right) + \frac{1}{4}\cos\left( \frac{1}{2}t + \frac{\pi}{3} \right) + \sin^2(t) \end{equation*} Determine the period ##T## and fundamental frequency ##\omega_0## of ##f## and draw images of its amplitude and...

Hi. I'm taking a look at some lectures by Charles Kane, and he uses this simple model of polyacetylene (1D chain of atoms with alternating bonds which give alternating hopping amplitudes) [view attached image]. There are two types of polyacetylene topologically inequivalent. They both give the...

Hi I have an engine that has three phase 18 pole stator for DC fired cdi system . I want to install it this engine in another bike frame the issue is that that frame has ac fired cdi wiring system. Where there is a special coil for the Ignition, lightning and charging. Can i covert the...

2. Relevant equation The Attempt at a Solution I can see straight away that the waves are 90 degrees out of phase so pie/2. But how is X ahead of Y? It looks like Y is ahead of X by pie/2.

Homework Statement For a balanced star connection i have given angles for V1=90 V2=0 V3=-90 i have to find the voltage required to produce the same phase currents as in standard three phase voltage source e.g V1=120 V2=0 V3 =-120 Homework EquationsThe Attempt at a Solution Im not even sure...

Hello! I was reading a paper on formulation of QM in phase space (https://arxiv.org/abs/physics/0405029) and I have some doubts related to chapter 5. It seems to me that there is a transformation to modified polar coordinates (instead of radius there is u which is square of radius multiplied by...

There is a question that has been bugging and puzzling me for a long time and I wondered if somebody could help me to figure out what the answer is or where I am not thinking straight. Let us assume that the standard model of particle physics is more "right" than "wrong" and there is no such a...

A friend has a ?40-50 kVA, 240 V, single phase generator, of 1970s vintage, coupled directly to an engine. It was working fine but now produces no power at all. All the brushes and spring holders are fine, as are the fuses. I can't find a decent description/diagram of the internals, other than...