Currents Definition and 476 Threads

In Griffith's EM text, he devouts 2 pages to deriving the equation for bound currents, and for the next 4 problems, he (the solution manual) doesn't even use the equations just introduced. I question the wisdom of deriving an equation that is harder to work with than we already had...

Homework Statement Determine the magnitudes and directions of the currents in each resistor shown in the figure. The batteries have emfs of ##\varepsilon_1 = 9.1## V and ##\varepsilon_2 = 11.6## V and the resistors have values of ##R_1 = 15 \Omega## , ##R_2 = 33 \Omega## , and ##R_3 = 30...

Homework Statement What are the sizes and directions of the currents through resistors (a) R2 and (b) R3 in Fig. 27-42, where each of the three resistances is 4.0 Ω? Homework Equations ΔV=IR The Attempt at a Solution Equations: 1) ΔVB2 -(i1)R1 -(i2)R2 -ΔVB1=0 5V - 4(i1)...

Hello Experts I have a question regarding high amperage going through strands of wires. For example, when hundreds of amperes surge through a thick cable of wire containing multiple copper wires, why is it that the current did not choose to go through just 1 of these strands of thinner...

I am still trying to solve this but I first, I need someone to explain to me about the sum of the currents, which I don't understand. The phasor of current I1 is 2+3j[A], and the phasor of current I2 is 1[A]. 1) Find the value of impedance Z. 2) Let the phase difference (arg(I3/I4)) between...

In my textbook it tells us ∫B ds = I μ (line integral and I = current enclosed) It also states that the current not enclosed does not affect the magnetic field along the line. I don't see a reason for other currents outside the loop not to affect the magnetic field thanks for any help

[SIZE="6"]Has to be done using KVL and KCL ONLY The attempt at a solution I first wrote down the KCL for the node 1 i.e the node above the 18 ohm resistor. Here's what I get 5.6A - ia - ib + 0.1vx - ic - 2A = 0 Here, substituting for 0.1vx as 1.8ia, I get: 5.6A + 0.8ia - ib - ic...

when current passes a conductor? does it also generate an electric field with a magnetic field? also what is the difference between the two fields?(i searched it up but i still don't get it) also are electric fields harmful to humans?(are they the same as radio waves?)

The figure shows a transistor with a bias circuit. If Ic=50IB and if VBE=0.7V, find VCE. My question is: The current through 700Ω resistor is H=[0.7+(51IB(250))]/700, then when KCL is applied at the left hand node, the current flowing through the 3kΩ resistor suppose to be (according to...

Can you help me explain this part from my book? In equilibrium, the pn junction has no external connections, i.e., the terminals are open and no voltage is applied across the device. If so, I wonder why there is drift current in the equation above. In equilibrium, the total current is zero...

How does this man get his currents? 1. Homework Statement [/b] I'm having a time trying to figure out how these currents are made. I don't understand his notation. It seems simple, but it is going the opposite way of what it should be doing because of the diode, right? Attached is the...

Hi, I am about to sit my Physics A-level paper next week and I have a couple of questions. My first question is rather broad, but what are eddy currents? I understand they're formed in transformers and how their effect is reduced, but I don't understand exactly why they're caused. Am I right...

Homework Statement Sandra needs to deliver 20 cases of celery to the farmer's market directly east across the river, which is 32 km wide. Her boat can move 2.5 km/h in still water. The river has a current of 1.2 km/h flowing downstream, which happens to be moving in a southerly direction...

Homework Statement The problem that this thread is about is problem 4.5 which is in the 4.5.jpg file (which makes reference to problem 4.2 which is in the 4.2.jpg file). Homework Equations ##R_{transfer,ij}## = ##Δ_R## / ##Δ_{ij}## The Attempt at a Solution This concept of "transfer...

Homework Statement Find the three mesh current. Homework Equations KVL The Attempt at a Solution I numbered the loop 1 with 2 and 3 ohms, loop 2 with 3, 5, and 212 V, and loop 3 with 3, 122V, and 5. All currents are clockwise. So for Loop 1: 2i1+3(i1-i2)=0 Loop...

Homework Statement An impedance of 7-2jΩ and an impedance of 4+2jΩ and a current source of 97.5A are all connected in parallel. Find the individual branch currents. Homework Equations Current-divider rule: I1=I*Z1/(Z1+Z2) (only have to consider the magnitudes of the impedances, not the angle)...

I'm confused by the fact that for the typical non-inverting amplifier, (1) The input current is ideally 0 A. but (2) The current going into ground is given by Vin/R1 where R1 is the resistor above ground. If Vin were provided by a battery for example, which has Voltage=0V on one side...

In DC circuit currents can be added if they meet at some point, but in AC current in resistor, inductor and capacitor differs, becase they are out of phase, can they be added?

hi all. I understand wikipaedias explination of eddy currents but could someone please explain more fundamentaly how they work. Thanks in advance :)

1. Homework Statement [/b] A solid cylindrical conducting shell of inner radius a = 4.9 cm and outer radius b = 6.1 cm has its axis aligned with the z-axis as shown. It carries a uniformly distributed current I2 = 7.4 A in the positive z-direction. An inifinte conducting wire is located along...

Hey Pf.. I am trying to understand Lenz's law, but somehow it doesn't make sense. In my book there is some checkpoints execise to test wheather you've understood what you read about, one those checkpoints looks like this. http://snag.gy/NCNLh.jpg I do understand why the current in...

2. Three loops of wire move near a long straight wire carrying a current as in the following figure. (a) What is the direction of the induced current, if any, in loop A? a. clockwise b. counterclockwise c. No current is induced. (ANSWER) WHY IS "C" THE ANSWER? I don't understand...

How should I think about symmetry currents?... in particular, when there are no fields to "carry the charge", eg in a pure Maxwell theory or, maybe, in a CFT of free scalars? Perhaps it would help if someone elucidated the connection between the "charge" in Noether's theorem and the "charge" in...

Homework Statement http://imageshack.us/a/img90/4018/homeworkprobsg25.jpg Find the three mesh currentsHomework Equations V = IR, KCL, KVL, Mesh / maybe nodalThe Attempt at a Solution I'm not quite sure how to set up the equations but I#1 = 4A right off the bat, for sure. I may need some...

Homework Statement Question: Find the current in the circuit shown. http://i1307.photobucket.com/albums/s599/JustOn4Fun/PhysicsFigure_zps39d4c66d.png Homework Equations Not sure if equations are necessary since it's a question testing the use of the following rules: Junction Rule The...

Homework Statement Consider two infinitely long cylinders with radius a and b and currents: J = (Jo r)/a for r less than a -Jo for a less than r less than b Find the magnetic field in 1) r less than a 2) a less than r less than b 3) r greater than bHomework Equations The...

Homework Statement The problem and its solution are attached. Homework Equations V = RI R_eq = 1/R_1 + 1/R_2 + ... + 1/R_n (Parallel circuits) R_eq = R_1 + R_2 + ... + R_n (Series circuits) The Attempt at a Solution For the two lines of math below “Now referring to the reduced...

Homework Statement I’m having trouble with analysing the transistor circuit attached to find VC, VB, VE, IC, IB and IE. Homework Equations These equations are taken from a previous example VE = VBB – VBE IE = (VBB – VBE)/RE IB = IE/β+1 IC = β/(β+1) x IE VC = VCC – ICRC β=100...

Homework Statement In the circuit shown in Figure Q8 below, if Vs = 10V, use Kirchoff’s Laws to determine the currents i1, i2, i3 and the source current is. Calculate the power dissipated by the resistors in this circuit. Confirm that the power dissipated by the resistors is the same as the...

Two infinitely long wires separated by distance d. Currents: I1 = -I2. Find potential vector as a function of r1 and r2 at a point P (r1 and r2 distances to P from wire one and wire two). Del cross A= B B = (mu I)/(2pi r) Using Ampere's, I get an expression for the magnetic field that...

Homework Statement What is the current in the 18 Ohm resistor in the figure below? What is the current in the 12 Ohm resistor? Please determine the directions of currents as well. What is the power dissipated in the 4.5 Ohm resistor? What is the equivalent resistance of the circuit shown...

Homework Statement What currents are provided by the batteries? What is the voltage drop across the 1.2 Ω resistor? Homework Equations V = IR Junction Rule = sum of current at a junction = 0 Loop Rule = sum of changes in potential around any closed path of a circuit must be 0 The...

I read in a paper http://nngroup.physics.sunysb.edu/~nngroup/misc/Documents/NeutrinoReactionsAtAcceleratorEnergies.pdf that delta_I = 1/2 rule of the strangeness-changing weak current implies the ratio of cross section of proton->Ʃ0 process to neutron->Ʃ- process to be 1/2. The delta_I = 1/2...

I read in a paper that delta_I = 1/2 rule of the strangeness-changing weak current implies the ratio of cross section of proton->Sigma0 process to neutron->Sigma- process to be 1/2. I do not understand what is this selection rule and how does it effect the cross section ratio of the 2 processes...

When you work with an emf of the form: U(t) = a0 + Ʃaicos(\omegat) it desperately cries for using Kirchoffs law for each term in the sum independently. I guess you can do so since Kirchoffs law is linear but then other the hand I get something weird physically when doing so. In every...

hi everyone, I have been trying to understand gauge theory. I am familiar with the Noether's theorem applied in the context of simpler textbook cases like poincare invariant Lagrangians. This is my question: Are there Noether currents corresponding to the local gauge symmetries too and would...

Homework Statement Determine ib and ia Ix = 0.4 mA, R1 = 15k ohm, R2 = 19k ohm, R3 = 23k ohm, R4 = 15k ohm Homework Equations V=IR The Attempt at a Solution I am assuming there are 4 unknown currents in this diagram. Ix splits into ib and i1. 0.4mA - ib - i1 = 0 i1 - i2 =...

I've read his book and he talks about AC current frequencies of incredibly high magnitudes. How was this achieved? Surely he did not just spin his dynamo really, really fast.

Homework Statement http://img846.imageshack.us/img846/955/29278644.jpg The Attempt at a Solution Basically I want to know whether my working method was correct as I have doubts with some of it. I first did voltage division at the two base resistances, and I get 3V at the base. Since we know...

Hi. Can someone please explain/tell me what would be the resulting currents trough the coil in every of the three depicted scenarios in the attached picture, I'm confused here. Would the first and the second drawing produce the same result? Is there any current flow in the third drawing. Thanks.

Find the currents i1 and i2 in the circuits ,see fig. v = iR ohms law -1.5 + i1 + i2 = 0 kirchhoffs law What should i do to find i1 ? http://s716.photobucket.com/albums/ww168/Pitoraq/?action=view&current=DSC_0202.jpg

Homework Statement I have attached the circuit diagram to this thread. V=12V, R1=2kΩ, R2=2.7kΩ, R3=1kΩ, R4=5.1kΩ. Find I1, I2, I3, I4, I5, I6. Find VA, VB, VC, VD. I just don't know how to apply kirchhoffs law to find the current and the voltage. I don't expect to have all answered. If...

Off the Wikipedia: "...in a copper wire of cross-section 0.5 mm2, carrying a current of 5 A, the drift velocity of the electrons is on the order of a millimetre per second." Suppose we have a setup with a very very light wire which can transmit very very high currents. Once the current is...

Homework Statement I have to find the currents in the three phases and the neutral. I understand that it has got something to do with Kirchoffs law, but how on earth? I can simulate it in multisim, and i get the right results for I_rms but i cannot figure out how to calculate. N->L...

should the current still be conserved? since it stills commutes with the Hamiltonian and symmetry is just hidden. but I just read that the linear-σ model was invented to demonstrate how the axial current could be partially conserved? Thanks!

Let`s say we have rotating body in the space which is covered completely or partially with some liquid.For example water.Rotating body do not exibits gravitational or tidal interation with other bodies.Will Coriolis force generate some constant currents in liquid or not? Please answer if you...

I'm reviewing transformers and I have some confusion over the current s is for secondary and p is for primary I know that Vs = Vp(Ns/Np) and Ip = Is(Ns/Np) So when you have a load across the secondary terminal you get your current through Vs/Rload. But does this mean for current in...

Hey guys, Been struggling with this for ages any help would be awesome. In Electrical engineering; Suppose you have a balanced multiphase star system with a given line voltage. The impedance of each phase is also know. If one of the coils is short circuited, calculate the line...

How Eddy Currents Produce Attractive Electromagnetic Forces--Maglev Hello, I am working on a paper about maglev systems and am trying to describe attractive electromagnetic suspension systems, but I am having a little trouble exactly visualizing how this works, which from what I have read is...

Homework Statement 50 volts, 60 Hz http://peecee.dk/upload/view/363429 I have to find the current through R, C, and L. Total current. Totalt impedance. Homework Equations I=(U/Z) The Attempt at a Solution See picture: http://peecee.dk/upload/view/363430 For I_R it must...