Phase Definition and 1000 Threads

Homework Statement I have an AC RLC circuit with the inductor in series with parallel capacitor and resistor. At what w is the emf in phase with the current? Homework Equations The Attempt at a Solution I'm suppose to know this from a previous class but as a transfer student...

Homework Statement Say you have a small boat moving through water, and creating a short wave-group which is a superposition of waves in the range of 0.2m-2m. If the shore 50meters away, how long will it take the fastest of the wave-components to reach shore? {assume the depth is constantly very...

Homework Statement Describe how the Fraunhofer diffraction pattern of a grating depends on: (a) the spacing between the grating lines; (b) the overall extent of the grating; (c) the amplitude distribution over an individual line; (d) the phase distribution over an individual line. A...

I'm working on an assignment due next Thursday and I'm having a little bit of difficulty on two problems that seemed surprisingly easy on the surface. My difficulty lies primarily in making sure I understand what the problems are asking. Here are the problems and I'll detail my idea without...

Hello, I am trying to figure out the transfer function for an RC phase shifter: http://imgur.com/2dnRYn7 (Picture of circuit) I am not sure how to calculate the output and specifically the phase of the output of this circuit. I understand that I need to consider one of the 'golden rules'...

Homework Statement The other day in lecture my professor mentioned the words mode locking and phase matching (same as velocity matching apparently) while on the topics of lasers. However, i can't find anything that can provide a simple explanation of what they are. Is there anyone who would...

I have three elements, A, B, C, that under certain conditions (rapid heating and cooling) form one ABC phase solid. Sometimes when I add a fourth element, D, I get two phase (AB,CD) solid. Obviously this phenomena is thermodynamically favourable. My guess (still undergraduate) is that there...

I have trouble understanding how to draw phase portraits. Is there a good pedagogical overview of their basics (such as elliptical vs hyperbolic orbits, separatrices etc.), along with an algorithmic way of how to draw them when it is not easy/possible to find v(x)? Basically something explaining...

I'm making a system with PLL. Here's more or less a principal scheme. What happens here is that the signal in this compensating system becomes really low and phase detector might not work properly. What I want to ask, what type or how to make a phase detector which can detect phase correctly...

Homework Statement https://scontent-b-dfw.xx.fbcdn.net/hphotos-prn1/v/1012733_10201076259690370_236735593_n.jpg?oh=4896ca67a34d3b223b764aba8ed308ab&oe=528A1B57 Homework Equations http://upload.wikimedia.org/wikipedia/commons/3/34/Phase-diag2.svg The Attempt at a Solution Not sure entirely...

Homework Statement There is a solid that can be in two phases, with energies U1(S,V) = S2/a1 + b1V(V-2Vo) and U2(S,V) = S2/a2 + b2V(V-2Vo). Consider a phase transition between the two phases at zero pressure. At what temperature, T0, does it occur? Homework Equations T = ∂G/∂S...

In an LCR circuit (circuit with inductor, capacitor and resistor), are the following statements always true? The capacitor voltage always lags the resistor voltage by a phase difference of 90°. The inductor voltage always leads the resistor voltage by a phase difference of 90°. The current...

I have no idea how to do this or where to start. Can someone please help me? Problem 4.4- Suppose n o and n e are given. In (a) you only need to find the magnitude of the group velocity. Problem #2 in HW 10 may be helpful. You can also directly use the definition of group velocity, i.e., v g =...

Hi, I've been reading a lot today about waves and how they have both a phase velocity and a group velocity. The group velocity makes perfect sense to me, I would phrase it as the speed at which the wave is propagating. The phase velocity on the other hand is quite confusing to me. What exactly...

Homework Statement A step down transformer, 2400/240 V, 50Hz has the following resistance and leakage parameters. Z1 = R1 + jX1 = 4 + j12 Ω Z2 = R2 + jX2 = 0.04 + j0.12 Ω The transformer is operating at 80% of its rated load. The power factor of the load is 0.866 leading. Determine the...

Hi guys I have been testing a brand new 250kw 3 motor wired in delta. I have it connected to a 170 amp vfd with no load for testing. It draws 105 amps at 50hz and is balanced. Intermittently the motor makes a strange that i have not heard before. It sounds like a spoon taping another...

Hello Homework Statement I have this tab http://img18.imageshack.us/img18/3317/eyph.png Anf I have to find the group and phase velocities for a wavelength λ=550nm Homework Equations v(phase)= c/n v(group)=dw/dk v(phase)*v(group)=c²/n² The Attempt at a Solution I don't know...

I did an experiment with two solenoids, one inside the other. The inner solenoid was hooked up to an AC power source and ammeter. The outer coil had a voltmeter. This is a faraday's law experiment. Because the current is changing, we can find a formula for the emf. Here are my math steps: So...

Hi all, When considering a half wave SCR rectifier (single phase) with an RL load, the term θ (conductive angle) appears in equations relating to the performance of the circuit. In terms what is physically happening in the circuit, what does θ actually represent?

I have this question on the calculation of the geometric phase (Berry phase) of a parallel transporting vector over the surface of a sphere, illustrated by Prof. Berry for example in the attached file starting on page 2. The vector performing parallel transport is defined as ψ=(e+ie')/√2...

Homework Statement "When only a resistor is connected across the terminals of an ac generator (111 V) that has a fixed frequency, there is a current of 0.465 A in the resistor. When only an inductor is connected across the terminals of this same generator, there is a current of 0.360 A in...

I'm merely starting to research this field. Phase transitions have always been a mystery for me. Which kinds of dynamics govern when a material will undergo a phase transition? e.g., why is it exactly at the temperature T0 and pressure p0 that the substance X goes from one phase to the other...

I have a problem in finding the heat transfer coefficient of a heat exchanger in which Ethane undergoes a phase transition. I would like to find the Prandtl number of Ethane in the phase transition region. So far I thought I would use the following: Pr_av = x * Pr_g + (1-x) Pr_l Pr_av =...

Homework Statement Find the attenuation constant alpha, phase constant β, and phase velocity v if the conductivity of the material is σ=ωε the material parameters are μr=1, εr =2.5, and the wavelength in free space is λ naught = 30cm Homework Equations The Attempt at a Solution So...

Dear all, This is a newbie asking for some information. Actually, we have 1x30HP, 2x10HP motors working at our workplace. When we start the motors there is a lot of torque generated due to which our grid supply charges us penalty every month. We need information about the device(s) that...

I was reading up on net metering, where the electric utility allows one to feed back excess generation by solar panels etc. onto the distribution network. http://en.wikipedia.org/wiki/Net_metering One question I had is, is it fairly easy to match phase for such inverters with the grid...

Homework Statement An EM wave normally shed on a conductive material (\tilde{\epsilon}=\epsilon+i\epsilon_i,\mu_0). Calculate the phase shift of the electric field of the reflected wave relative to that of the incident wave. Homework Equations...

Can anyone please provide an intuitive explanation of why phase shift of 180 degrees occurs in the Electric Field of a EM wave,when reflected from an optically denser medium and also why the phase remains same on reflection from a denser to rarer medium? please try to explain on an atomic/sub...

Hi guys I have a rather qualitative question. let's imagine a tank with two openings. pressure is measured at one opening (A) to be at a constant 33 bar at time t=0s. the other opening(B) is at atmospheric pressure. Inside the tank we have a two phase flow half is N2 gas and the other half is...

In almost every QFT or particle textbook we learn that complex scalar fields or spinor fields (or even multiplets of spinor fields) have a phase symmetry (global gauge symmetry.) You can append to these fields an exponential with a complex phase in the Lagrangian and the dynamics remain the...

Hello, As it says in the title, I would like to know if the light entering a twisted nematic liquid crystal display experiences any kind of phase shift specifically when applying a voltage to manipulate the polarisation of the light. If it is the case, could someone point me towards any...

Homework Statement I'm working on a Matlab problem for a digital image processing class. The problem is to take an image, then take its 2D-FFT and offset the phase component by pi. Then to take the IFFT of the new DFT using the unmodified magnitude and modified phase. What I got was a...

why is the phase velocity(c^2/v) greater than c?? since v<c it should be greater than c.. how does this happen?

I am a graduate engineer and have been set a small task to work out the current (primary side) in a 2 phase 30kVA 415:650 transformer. The 2 phases have been utilized from a 3 phase source and are hence 120 degrees out of phase. I understand had it been a 3 phase 30kVA transformer I could...

I'm wondering about small changes of phase due to a refractive medium. For example, suppose there is an emitter of radio or light waves, and two detectors equidistant from the emitter. One of the detectors is behind a medium, while the other is a straight shot through a vacuum. How would...

It could be possible for a driven vacuum bubble (like an Alcubierre drive,assuming that it could be possible to realize ) to travel not only many order of magnitude faster than light but even trough different vacuum phase ? like for example region of false vacuum ?

Is it possible to check the phase rotation sequence of a Medium Voltage Motor (Up to 6 kV) with one instrument? Does the shaft need to be moving while it is being tested? If instead of one, there are two motors electrically connected in parallel, with a common source feeder. will it be...

Homework Statement http://icho2013.chem.msu.ru/materials/IChO-2013_Theoretical_Official_English_Version.pdf Looking at problem 1. Homework Equations The integrated form of the Clausius-Clapeyron equation: ln(\frac{P_{T2}}{P_{T1}}) = -\frac{\Delta H}{R} \cdot (\frac{1}{T_2} -...

Homework Statement 1. A signal of the form x(t) = A cos(ω0t + φ) is plotted below. From the plot, deduce the following: (a) the amplitude A, (b) the period T0, (c) the radian frequency ω0, and (d) the phase φ in radians. For part (e), find f0 in Hz by converting the radian frequency from part...

note: Phase I is just safety testing, not efficacy. Still exciting, though! http://communications.uwo.ca/media/releases/2013/September/no_adverse_effects_in_volunteers_following_phase_i_clinical_trial_of_sumagen_aids_vaccine.html

When a single phase 415 / 480 volt load is connected, one Kw/h meter will turn in the right direction whilst the other will turn in the reverse direction. This is the case whether the load is a welder or flood light or inductive heater. Can anybody please explain the reason why?

Homework Statement Currently, I'm doing on a research of this three phase PV grid tied system. I found a model and try to run and simulate for further understanding. There's an attachment of a model three phase pv grid tied system in Simulink. However, I've a hard time understanding the MPPT...

I have read that the rear surface reflection of a half-silvered mirror undergoes no phase shift. But they caution that this is true only for a dielectric mirror. What is the answer for a metallized mirror? It seems to me that the answer must either be 180 degr., or pass continuously to 180 degr...

I am reading a text about how MRI works and I came across a thing that I am totally confused. The book mentions about that few particles side by side with their nuclei spinning at the same frequency but they all have a phase difference. Since MRI cannot measure the phase differences directly...

Hello there, I have been searching for MATLAB simulations that analyze optical cavities and there are some useful codes. Yet, I haven't found codes that analyze what happens to cavit transverse modes if spatially dependent phase is introduced between mirrors Does anybody know if there...

Homework Statement Given tthe following voltage and current i(t) = 5sin(377t - 20°)A v(t) = 10cost(377t + 30°)V Determine phase relationship between i(t) and v(t) Homework Equations wave functions wave properties The Attempt at a Solution Would the phase relationship simply be 50°...

Hello Everyone, I was wondering if anyone out there would know any kind of phase synchronisation techniques used in mobile/satellite communication. Thanks in advance With Regards, Max

I have a linear model of a phase detector (phase lock loop) represented by the block diagram below. It is designed to maintain zero difference in phase between the input carrier signal and a local voltage controlled oscillator. Phase demand→Ka→F(s)→K/s→Phase output F(s) =...

k being the one from the harmonic wave ψ(x,t) = Asin(kx - ωt) where k = 2π/λ The way I see it right now, k is just defined this way to get the period of sin(x) to be λ by using sin(kx), so I wondered if there's something more to it. (Though I know it can be used as an vector to declare the...

Dumb question - if the phases are tied together in a three phase delta transformer why don't the phases short out against each other in the same way the transmission lines would fault phase to phase if the touched each other in the overhead? I think I understand the wye winding situation in...