Currents Definition and 476 Threads

Hello, I am a mechanical engineer by education and I am working on a multi disciplinary problem. I regularly work with eddy current dynamometers at work and I am curious about the materials used within the rotor and stator of these dynamometers. First off, this isn't a homework problem per...

Throughout the electric force/field and magnetism unit, there's always a rule that involved using the left hand and the right hand. I'm a bit confused on how to apply the rules because of the units are applied to different fingers. If someone could give me an explanation on it, that'd be great...

I have these two circuits with permanent rule: a) b) I'm asked to find: For a): the charges of each capacitor (C = 1 \muF)and the currents in each resistance. For b): the currents in each branch with the L switch on and off, the difference of potential between A and C, A and B and C...

A circular wire ring of diameter 18 cm carries a current of 5.0 A directed as indicated in Figure P.51. A moving electron just happens to be passing through the neighborhood. When the electron is at the center of the circular ring and moving at speed 2.50 multiplied by 106 m/s in the direction...

Two infinitely long straight wires lie in the same plane and carry the currents depicted in Figure P.48. (a) Find the magnetic field at the point P located 24 cm from the intersection of the wires along the bisector of the acute angle between them. (b) Find the magnetic field at the point S...

1. In the circuit of the figure, find the current supplied by the battery. 2. Find the current through the 6\Omega resistor. Attempt at a solution: To find the total current supplied by the battery I tried: \frac{6*4*2}{6+4+2} = 4\Omega Then I did that resistance in series with...

Not sure if this is the right place to ask, but this doubt originated when reading on string theory and so here it goes... The general canonical energy-momentum tensor (as derived from translation invariance), T^{\mu\nu}_{C} is not symmetric. Also, the general angular momentum conserved...

Hello, I'm not sure where to post this so I hope this is the right spot. It's not a homework question, just a concept I need to get straight before an exam ;) If I'm pulling a sheet of metal through a uniform magnetic field (which is perpendicular to the sheets motion), Eddy currents are...

Okay, I'm sure I must have overlooked something very trivial, so please help me with this: Two parallel infinite line currents of equal magnitude attract each other. The current can be thought of as consisting of positive and negative particles with equal linear densities, but each moving with...

Okay so i just want to make sure i got this right because its a kind of confusing topic for me. So eddy currents are caused because when there is a motion (with a conducting surface) through a magnetic field a current is induced? and because there is a current there is also a magnetic field due...

1. A 50 g horizontal metal bar, 12 cm long, is free to slide up and down between two tall, vertical metal rods. A 0.060 T magnetic field is directed perpendicular to the plane of the rods. The bar is raised to near the top of the rods, and a 1.0 Ohm resistor is connected across the two rods at...

Iv started physics electronics literacy at university as a requirement for my degree, i didnt do science at school and I am very confused with what's going on..How to a determine a current in the resistors, please can someone give me a step by step on how they got to the answer...i have uploaded...

Homework Statement I have to show that the vector current \vec{V}^\mu = \overline{\psi} \gamma^\mu \vec{T} \psi and the vector axial current \vec{A}^\mu = \overline{\psi} \gamma^\mu \gamma_5\vec{T} \psi satisfy this \partial_\mu \vec{V}^\mu = i\overline{\psi}[M,\vec{T}] \psi...

(Solved.) 2 Unknown Currents, 1 Unknown emf, and a little confusion to boot! First off, hello everyone! I just formally joined the forums today after reading discussions from the shadows for a while now. This summer I'm taking the second part of a 200 level physics course and the...

A number of years ago I required a low voltage, extremely low current, voltage regulator. Normal Zener diodes do not function well at low currents. I became aware that the forward voltage of red LED's was approximately 1 Volt at even extremely low currents (less than 1 microamp). My...

I've read that when currents in two parallel wires are going in the same direction, they attract each other. The same text said that when the currents are going in opposite directions, the two wires repel each other. now i can't porve this for myself as i keep making the folowing mistake can...

I'm guessing it has something to do with the fluid gaining thermal energy from the heat, the heat makes the molecules repel each other further so the fluids volume expands? if not why do fluids expand with heat? - the rest is mandatory, after expanding the volume increases, decreasing the...

Homework Statement Consider two small conductive spheres in radius a and b located far from each other. In t=0 "a" sphere charged with Q and "b" sphere neutral. We connect the spheres by wire with resistance R. Find the charge on each sphere as a function of time. Homework Equations...

given the following: http://lh6.ggpht.com/_H4Iz7SmBrbk/Sg04JIIg9vI/AAAAAAAAA-o/xDycbG90Gmc/s720/C.jpg and given that ε1=3V ε2=2V R1=1Ω R2=2Ω R3=3Ω i am asked to find the current flowing throiught R1,R2, R3 what i did was I3=I2+I1 I1R1-I2R2=ε1 but i am short of one...

Homework Statement A capacitor is charged through one bulb and then discharged through two bulbs. Mark each of the following statements true or false. a) The same amount of charge flows during charging and discharging. b) More charge flows through the single bulb than through the two...

Homework Statement A coaxial cable has a linear insulating material of magnetic susceptibility \chi_m separating the conductors. A current I flows down the inner conductor and returns along the outer one. Find the magnetic field in the region between the tubes. As a check, calculate the...

Homework Statement Your friend wants to be a magician and intends to use Earth's magnetic field to suspend a current-carrying wire above the stage. He asks you to estimate the minimum current needed to suspend the wore just above Earth's surface at the equator (where the Earth's magnetic field...

Homework Statement Find the three currents in the image. Homework Equations Khirkoffs laws Sum of currents equal zero. The potentials around a closed loop add up to zero. The equations given in the solution are -2I_1 + 12I_2+6=0 -12I_2+8 = 0 I_1+I_2+I_3=0 The Attempt at a...

Homework Statement find the current in I3 and I2 and I1 Homework Equations junction Rule The Attempt at a Solution Loop 1 : -I1(4.1) + 29V - I1 (3.3) -I3(2.9) -I1(7.4) -I3(2.9) = -29V Loop 2 : I3 (2.9) - I2 (5.5) +16 V - I2(2) -I2(7.5) + I3(2.9) = -16 V Loop 3 : -I1(4.1) +...

Homework Statement Is the current at all points the same? If not then what is the order from highest to the lowest? http://img141.imageshack.us/img141/2418/currenthn9.th.jpg Homework Equations The Attempt at a Solution

Hi all -- I'm writing a controller for an interferometer and I need to be able to control the voltage across a terminal and read the current from a photodiode in c++. What would be a good, reasonably priced peripheral that would accomplish this, preferably with linux support? Better yet, is...

Hey, I have this QTI sensor ( circuit is shown, the left schematic ) and I am trying to get it to detect a white line only, no red,blue or green just a white line. 5 volts is applied to the pin called White(top pin). Now when the IR light is emited from the IR LED will the Ie, emiter current...

Out of curiosity is it possible to generate a split second of an electrical current which would be more of an electrical signal by literally boucing an electrical conductor off of another electrical conductor, such as copper hitting copper sending the electrons flying down the current or would...

Homework Statement Hi all. Please take a look at the attached circuit. I've have found the amplitude of the current through the resistance to be: \left| {I_0 } \right| = \frac{{\varepsilon _0 }}{{\left| {R - \frac{R}{{\omega ^2 LC}} + \frac{i}{{\omega C}}} \right|}}, where ε_0 is the...

Homework Statement The preceding problem was an artificial model for the charging capacitor, designed to avoid complications associated with the current spreading out over the surface of the plates. For a more realistic model, imagine thin wires that connect to the centres of the plates (see...

Hello everyone! I have been searching all over the internet for an answer to this question: will moving a magnet within a coiled wire induce a current even if the magnet "stays" within the coiled wire for a matter of seconds? I am planning an improvement to an experiment where a magnet...

Homework Statement A fat wire, radius a, carries a constant current I, uniformly distributed over its cross section. A narrow gap in the wire, of width w << a, forms a parallel-plate capacitor, as shown in the figure above. Find the magnetic field in the gap, at a distance s < a from the...

I've been playing around with the QCD Lagrangian to get a better understanding of how it works. I can derive some classical, Maxwell-like equations; the inhomogenous ones are \nabla \cdot \vec E^a = -gf^{a}_{bc} \vec A^b \cdot \vec E^c + \rho^a \nabla \times \vec B^a -...

Consider this quote from Mandl and Shaw, p. 237 ...this interaction coulpes the field W_{\alpha}(x) to the leptonic vector current. Hence it must be a vector field, and the W particles are vector bosons with spin 1. Could someone explain this for me? I do not understand the "hence"...

Not a homework question, Just trying to get more information about it. Its hard to find a textbook or a site that explains this well. thanks

i've just had this thing running through my head that I'm trying to resolve: 1. two parallel wires that conduct a current (same charge carriers) will attract one another, that is the magnetic force each wire emits due to the flowing current will induce an attractive force in the other (charge...

HF HV to LF? I wanted to say that I have searched the site and it is very imformative, glad to be apart of it. That being said I had a question, what means would you use to convert high frequency currents to that of line current(60hz)?? I have searched and searched on google and have not...

Homework Statement A long current-carrying wire, oriented North-South, lies on a table (it is connected to batteries which are not shown). A compass lies on top of the wire, with the compass needle about 3 mm above the wire. With the current running, the compass deflects 10 degrees to the...

Homework Statement For the three (simple?) circuits, I'm asked to solve for the voltages at A and B, and also the current I. For figure 1, I assume that is just a simple voltage divider, with the voltage at A to be 5*(1/21) correct? I'm a little more confused with the circuit in figure...

Homework Statement From serway's book chapter 23(electric fields), questions section. Homework Equations --- The Attempt at a Solution The obvious answer would be that it is safe because the student holding the sphere is insulated from the ground, but what does that really mean ? If I try to...

Homework Statement Two negative charges repel each other. Two parallel wires with current going in the same direction attract each other. Yet if one walks with the moving charge in the wires, the charges appear stationary and should repel each other - explain why if you are stationary...

Homework Statement An uncharged 1.15 uF capacitor is in series, through a switch, with a 4.50-M Ohms resistor and a 24.0- V battery (with negligible internal resistance.) The switch is closed at t = 0 and a current of Ii immediately appears. (Which I calculated to be 5.33 uA.) How long will...

Hi All! I am working on the Eddy Currents problem. I was to set up the problem and derive some equations for the pivot pendulum with Eddy currents. Please see attachment. As you see the pendulum swings between max point ( just outside the B field) and enters the B field and then...

Hey all, I was wondering about a varied version of something. I know that if you run a magnet up and down a tightly coiled tube of copper, it creates an electric current through the wire. I also know the reverse, which is that if you passed a current through that wire, while it was wrapped...

Hi Everyone seems to know what magnetic fields are and that they are caused by electric currents, but i can't seem to find a good reason WHY they are caused by lectric currents. Thanks, appreciated

Hi Everyone seems to know what magnetic fields are and that they are caused by electric currents, but i can't seem to find a good reason WHY they are caused by lectric currents. Thanks, appreciated

I am not asking if they are considered as input into the armature's magnetic field. I strongly believe they are NOT even considered when designing motors. The question is, "DO THEY EXIST IN MOTORS?" Based on evidence from conventional theory, it appears they do infact affect the output of...

Attached is a picture of the object that I am trying to figure out the forces due to currents that will be acted on it. Here are the questions I have ( I really just need some direction in the area of appropriate formulas) 1) what are the force againts the surface of the collector in foot...

Homework Statement What observation of the process: (anti muon neutrino) + (electron) -> (anti muon neutrino) + (electron) constitutes unambiguous evidence for weak neutral currents, whereas the observation of (anti electron neutrino) + (electron) -> (anti electron neutrino) +...

From EurekAlert, 16 April. Mysterious striped currents in our oceans IT’S amazing that nobody has spotted it before. Superimposed on every ocean on the planet there is a striped pattern of currents. Yet what causes them is a mystery. Between 1992 and 2003, Peter Niiler of the Scripps...