Currents Definition and 497 Threads

First I found the equations of motion for both fields: $$\partial_\mu \partial^\mu \psi = -\frac{\partial V(\psi^* \psi)}{\psi^*}$$ The eq. of motion with the other field is simply found by ##\psi \rightarrow \psi^*## and ##\psi^* \rightarrow \psi## due to the symmetry between the two fields...

Since ##\vec{R}/R^3 = -\nabla(\frac{1}{R}) = \nabla^\prime(\frac{1}{R})##, the standard form of the Biot-Savart law for volume currents can be re-written as: $$\frac{\mu_0}{4\pi}\int\limits_{V^\prime}\frac{\vec{J}^\prime (\vec{r}^\prime)\times\vec{R}}{R^3}d\tau^\prime =...

Hi all, so I had this problem and on the exam and I got a solution but I had an mass-term in there which wasn't given. I used Farraday's Law of Induction to get the Voltage induced. Then I used ##rho* \frac{A}{4a} ## for the resistance and divided the Voltage by that to get the current. I then...

Hi, guys, I am developing a simulation in Ansys Maxwell. I set up my simulation in the "transient mode", and I would like to evaluate the eddy currents that arise in a metal Vessel. The currents rise to a flat top in 20 ms and then after 20 ms in the flat top, it decreases to zero in 20 ms. I...

Hi, If there is an electrolysic in a vat, there is a positive and negative drift current betwwen the electrodes. Is it possible to have a situation where there is only one (either positive or negative) drift current? Thanks

I’m facing strange phenomenon in voltage multiplier operation – PCB traces are overheating. Multiplier runs at 50KHz, consumes 40V / 26A and delivers 500V / 2A. The prototype is continuously monitored by IR camera due to overheating concern. None of electronic components is heating...

Hello all, I understand the distinction between FLHR and FRHR. The LHR is used primarily for motors, while the RHR is used for generators/induced currents. For a conductor moving between magnetic poles, we can use the RHR to predict the direction of the induced current. According to the diagram...

I have a set of little flywheels that have a magnet to break the motion of the system. I have one aluminum and several copper ones all water jet cut roughly to size. The copper and aluminum disks I have are all the same dimensions but bought from three different sources. Yesterday I machined the...

Homework Statement For a configuration of charges and currents confined within a volume ##V##, show that $$\int_V \mathbf J d \tau = \frac {d \mathbf p}{dt}$$ where ##\mathbf p## is the total dipole moment. Homework Equations ... The Attempt at a Solution I have one question: since the...

I'm currently doing a course on the Standard Model and I think I've gotten confused on some of the symmetries and resulting currents. Here's my current understanding: Before SSB: Electroweak - U(1) symmetry on fermion spinors and Higgs complex doublet, 1 conserved current Electroweak - SU(2)...

Hello All, 1. Homework Statement I am confused about applying constant voltage drop model or iteration model . While trying to find the diode currents, results obtained from iteration is not consistent ( I_d1 and I_1k is not equal) so the diode currents . ALsoIs this convenient to use...

Suppose I had cylindrically-symmetric rotating magnet surrounded by a plasma. I rotate it on its axis at a constant angular velocity, and so the electric field E produced is non-solenoidal and can be described as the negative gradient of some potential V(x,y,z). The electric field is induced...

Hello. How would this be done? Using a step up transformer?

Suppose a 10k Gauss 3in diameter sharp magnetic field is made & collapses completely thru a standing human human body somewere made by an external electromagnet.. The electromagnet is held horizontally and not vertically against body. Is this hazardous? Can it become hazardous after some...

Homework Statement Homework Equations ##Q=CΔV## ##V=IR## The Attempt at a Solution Is my answer correct ?

Is like currents of opposite charge attract or repel each other

Homework Statement In the circuit of the figure, determine the intensities I1, I2, I3, I4, I5 and the voltage Ug. Homework Equations Superposition and Kirchoff The Attempt at a Solution 20-10I1+5I3-10I1=0 5I3+Ug+5I5=0 20I2+10I2-150=0 From the last equation, 30I2 = 150, I2 = 5 A KNOTS...

Homework Statement A circuit with current I has two long parallel wire sections that carry current in opposite directions. Find magneticfieldatapointPnearthesewiresthatisadistance a from one wire and b from the other wire as shown in the figure. Homework Equations B=μo*I / 2πR The Attempt...

I'm trying to use a solenoid to measure the magnetocaloric effect of dysprosium. The effect is highest at the Neel temp which is down near 180K. I have a solenoid in a cryostat to get the correct temperature. The cryostat's heat exchanger is made of a thick copper cylinder and I think it is...

Hello! I'm currently working on a project that will utilize the phenomena of eddy currents to apply a braking force to a rotating disk. Some background on this project: My team was tasked to create a physical therapy training device to train patients in wheelchair propulsion at resistances lower...

Homework Statement It's a solved problem but I don't understand why is there no 30 degree lag from line voltage to lead voltage. Homework Equations Phase voltage = Line Voltage / 1.732 and there is 30 degree lag So shouldn't Ir be at angle 150 degrees.The Attempt at a Solution In Y line and...

Hi people, me bother yo again! I understand that relativity theory length contraction is the explanation of magnetics fields. See the image: https://dl.dropboxusercontent.com/s/vuy69jhig3kni3n/densidadcargasencorriente.jpg?dl=0 1) In the S system, if q is moving at the same velocity than the...

Homework Statement Then solve these equations for i1-4 Homework Equations V=IR The Attempt at a Solution 80i_1-50i_2-30i_3 = -120 -50i_1+100i_2-10i_3-25i_4 = 0. -30i_1-10i_2+65i_3-20i_4 = 0. -25i_2-20i_3+100i_4 = 0. i_1=-4.18239492 i_2=-2.66455194 i_3=-2.71213323 i_4=-1.20856463...

Hi, In an AC 3-phase induction motor (i.e. asynchronous motor) rotating magnetic field is produced by the stator and in this case rotor consists of simple cage having metallic bars or with coils wound around the rotor. The rotating magnetic field magnetizes the rotor and attracts it. As the...

Homework Statement Homework Equations V=IR parallel resistance. The Attempt at a Solution All elements are in parallel (teacher confirmed this in explanation to the class). Beginning placing labels for nodes to the right of R1, A, B, C, D, and E (ending before R4) and redrawing it as the...

Homework Statement Calculate the value of the current through the 12 V battery shown in FIGURE 3. attachment-php-attachmentid-41345-stc-1-d-1322543216-jpg.147932 Homework Equations KCL KVL The Attempt at a Solution So, I1+I2=I3 [/B] Loop A (Left hand loop): +13-3*I3-12-I1=0...

Homework Statement In one of the most common examples of Lenz's Law a magnet is dropped inside a copper tube and due the induced emf and the eddy currents generated in the copper tube the magnet falls through it with constant velocity. The external force that the eddy currents oppose is...

Homework Statement I need to find the currents I1 and I2 in the attached image, but am having some difficulties grasping the concepts. I am given E(t) = 338sin(t) as well as values for R, L and C. I think I know what I need to use but I am not sure how to put it all together Homework Equations...

Hello there guys.I am currently doing an undergraduate degree in Mechanical Engineering and in order to graduate I have to do a major project by my choosing.So i I chose а magnetic brake, using eddy currents principle.We all saw that cool videos in youtube with magnets and copper tube.So i came...

Homework Statement An RLC circuit contains the following components in series: a 15Ω resistor, a 200μF capacitor, and a 12mH inductor. What are the currents and voltages through each component? It's known that the current through the resistor is 1.75A⋅cos(250πt) Homework Equations χL=ω*L...

Homework Statement Just problem 19C. Homework Equations P=IV=Ieiwt*Veiwt. T The Attempt at a Solution P = IVe2iwt=IVcos(2wt). What did I do wrong?

<Moderator's note: thread split off from https://www.physicsforums.com/threads/lhc-absence-of-supersymmetric-particles.917829/> I wonder how unexpected, or not, was the discovery of neutral currents.

Hello all. Thanks for taking up your time to read my post. I checked the currents that passed through several LEDs for MIC2287CBD5 as the datasheet of http://www.kynix.com/uploadfiles/pdf2286/MIC2287CBD5.pdf at a particular voltage. They varied from 12.0 to 15.1 mA at 3.0 V. I then connected...

Hello, Reviewing for the test and there are still some things I'm not sure about so I thought I'd ask here and hopefully come across someone that can help. I swear I knew this, but I have not been diligently reviewing as much as I should so I think I forgot and became confused. When a...

Homework Statement Homework EquationsThe Attempt at a Solution These are problem 5.1 (b) and the solution. I understood the gap between each loop is 1/N, but why does each loop have vertical direction current amount of I/N ?? [/B]

Hello, I was solving a problem related to Eddie currents recently and I need some help with simulating it numerically. Basically, we have a disc-like copper pendulum entering a region of uniform magnetic flux density B (see diagram). I understand that I need to use Faraday's law: \nabla...

Homework Statement Two parallel wires connected to equal sinusoidal alternating currents with a phase difference of pi rad. How does the force of attraction vary with time (draw a graph)? Q from here...

Homework Statement Find currents I1 and I2 in the following circuit: Homework Equations I know I have to use Kirchoff's loop rule but I am not sure of the current going through the 5 ohm and 8 ohm resistors, is it just I1 and I2 respectively? Also do I incorporate the large loop at the...

Homework Statement A Neutral copper Rod, a polarized insulator rod, and a bar magnet are arranged around a current-carrying wire. Will the neutral copper rod, polarized insulator, and magnet remain stationary?Homework Equations does the electric field of the current carrying wire have an...

So the picture is this. Basically an application of amperes law and Newtons third law shows that they attract.But what about from the frame of reference of the moving currents. Say I have a stream of charges moving to the right, and another stream of charges moving to the right. Both with same...

Homework Statement Homework EquationsThe Attempt at a Solution So far I was able to transform each element into the frequency domain: I am just unsure how to work with the dots to find the mesh currents. Can someone explain? Thanks.

Homework Statement The circuit of the given problem is attached to this post (jpg file). All info is given in the photo. Problem: find VA, VB, IA. Homework Equations Ohms law KCL equations P = VI or V^2/R The Attempt at a Solution - First, I noted that VB = 9 - VA. - next, i set up a KCL...

Homework Statement The diagram shown below shows a bi-directional opto coupler input interface circuit. When a supply voltage of 20 V is applied the LED carries a current and 2 V is dropped across it. Calculate the value of the LED current and the value of current through the 3 kΩ resistance...

I've always heard that maxwell's equations contains essentially all of eletromagnetic theory. However, there's one thing I'm having trouble doing for myself: deriving the magnestatics equations from the maxwell's equations. Of course: it's clear that if you put ∂[t]E=∂[t]B=0 (partial derivative...

Charles Link submitted a new PF Insights post Permanent Magnets Explained by Magnetic Surface Currents Continue reading the Original PF Insights Post.

Please help me with this. I am having a hard time understanding the role of displacement currents in a circus. The common knowledge is actual current is the movement of electron in a circus. Now, if there is a gap and an AC source, there would be an electric displacement field and a displacement...

Neodymium-Iron-Boron magnets have a relative magnetic permeability of 1.05. According to the formula: B = μ0 * (H + M) Both the magnetizing field H and the magnetization M contribute to the magnetic field B. The magnetization M has sources and sinks, so therefore it follows from Maxwell's...

Homework Statement Is a current that produces a magnetic field always going to be either an electron or a proton?

Homework Statement (a) Determine the current in each branch of the circuit. Homework Equations V=IR Summation of the voltages in a loop = 0 The Attempt at a Solution I have this problem figured out in general, but the only thing confusing me is the current in the middle. What exactly...

Suppose there is a solenoid near an accelerating electron. The electron must create a changing magnetic field. By Lenz's law, an emf is induced in the coil. One question is, how *fast* is the emf induced in the coil? Is the emf just there instantaneously or does it take time to formulate? And...