Wire Definition and 1000 Threads

Homework Statement In a current-carrying wire, the total net charge in the metal is zero. Why does the wire experience a force when placed in a magnetic field? Homework Equations The Attempt at a Solution The reason for the force is the motion of the electrons, not their...

Homework Statement Two isolated farms are 12km apart on a straight country road that runs parallel to the main highway 20km away. The power company decides to run a wire from the highway to the junction box, and from there, wired of equal length to two houses. Where should the junction box...

Homework Statement A uniformly charged wire or radius R1=0.02m runs down the axis of a cylinder of inner radius R2=0.06m. The potential difference between the wire and cylinder is 60 volts. Find the electric field at the surface of the wire. Homework Equations Electric flux=Q/\epsilon0...

Homework Statement I built an amplifier in the breadboard so I want to test it out. I know there is a type of wire that one side can connect to the ipod and the other side separate into power (red in color) and ground ( black in wire) But I forgot the name of the wire, so I want to ask if...

Lenz law problem wire and expanding loop Homework Statement The loop has current radius R the red bar moves at velocity V. The distance the wire is from the loop is d and the top of the loop is length l Find the induced emf and the direction of the current in the loop. Homework Equations...

Homework Statement Find the magnetic field at the point (the big dot in the picture) The curve is supposed to be a quarter circle and both wires are parallel and radius is R the wires are infinitely long Homework Equations Biot-Savart Law...

Hi there. I'm basically trying to understand why when 2 wires are place near each other, given a current in the same direction they will attract each other. I have read a this: https://www.physicsforums.com/showthread.php?t=39472 But I don't see how some say 'generates a magnetic field...

So let's say I have a wire of length l moving in a uniform magnetic field of constant velocity. Now the induced EMF = Blv Constant velocity implies constant EMF generated per unit time. I even have a graph of EMF vs time in my textbook for such a situation showing a flat horizontal line...

Given a cylindrical wire of radius r, length L, carrying a current I, find the total energy stored inside the wire. From griffiths, uem= εE2/2 +B2/2μ and the tot energy is ∫uem dV I have my E and B fields, but my B field is a function of x where x<r, (E is uniform) B=kx/r2...

Homework Statement A bead is free to slide along a rigid, straight wire, whilst the wire is rotating at angular velocity ω about the z-axis and is tilted away from the z-axis at angle α. I have the equation of motion (EOM) and need to find an explicit solution for the distance of the bead along...

A short question: Why and how is the line current equal to the phase current in the 3phase- 3wire system?

Given a cylindrical wire of radius r, length L, carrying a current I, find the total energy stored inside the wire. From griffiths, uem= εE2/2 +B2/2μ and the tot energy is ∫uem dVI have my E and B fields, but my B field is a function of x where x<r, (E is uniform) B=kx/r2 (k=all the...

Homework Statement Use Ampere's Law to show that the equation for the magnetic field inside a current carrying wire is (1/2)μJr where J is the current density (assumed constant). Homework Equations ∫B*ds=μI The Attempt at a Solution ∫B*ds=μI B*ds=B(ds)cosθ I think θ...

http://img850.imageshack.us/img850/3444/asdfga.jpg i'm used to approaching these questions by using either guass' law or amperes law but in this question i don't see how either will help since there's no enclosed charge its a current, and also since the whole wire carries the current and you...

Homework Statement If the current density in a wire or radius R is given by J = kr, 0 < r < R , what is the current in the wire? Homework Equations I used j = I/A, the definition of current density: current per unit cross sectional area. the formula for the area of a circle and for a...

I just saw one of these antennas, and I'm puzzled a bit by it. Why would one choose to use a parabolic wire antenna instead of a solid parabolic antenna? It would seem to be much less efficient at first glance (although I don't know if it is true or not). And how do the wire elements manage...

hello every body. I have a high school problem a straight horizontal wire is falling freely in a homogeneous horizontal magnetic field, perpendicular to the wire and i want to find the inductive voltage. I said E= Blv=Blgt But I can also say E=ΔΦ/Δt=BΔΑ/Δt=Βl1/2gt [t][2]/Δt=1/2Blgt why...

Hello all, Are there any cables that are immune and not affected by magnetic fields of the strength of 1-2 Tesla? Either simple current wires, or more complex ones like USB or Ethernet cables.

Homework Statement A 100kg sign is suspended by two wires with angles of 35˚ and 55˚ (to the roof) and meet at a 90˚ angle at the sign. Determine the tension in each wire. (I'm not sure if I described very well. It was on a diagram) Homework Equations Fg=mg aˆ2+bˆ2=cˆ2...

I've read about wire-grid polarizers from wikipedia. The article says that waves perpendicular to the wires cannot induce electron movement and hence they pass through with minimal energy loss. On the other hand, waves parallel to the wires are reflected by the wires because electron movement is...

I've read about wire-grid polarizers from wikipedia. The article says that waves perpendicular to the wires cannot induce electron movement and hence they pass through with minimal energy loss. On the other hand, waves parallel to the wires are reflected by the wires because electron movement is...

Modified microwave transformer- need advice for rectifiers and wire ratings. Hello everyone. I've been doing a lot of research as to how to go about purifying copper. There are two approaches I'm considering. Electrolysis and Smelting. The electrolysis method requires I have a DC output of low...

How to measure tension in guy wires? Could somebody please help/guide me in the right direction as to how I would go about measuring the tension in guy wires for a college assignment? I have been told that one method is to place some sort of rigid frame next to the cable, that touches the...

Hello, I am a new member here and am having a problem as to finding the more effective way to power my el wire. For those that don't know el wire is a thin copper wire coated in a phosphor which glows when an alternating current is applied to it. My goal is to wrap my bicycle in about 5...

Homework Statement A current-carrying circular loop of radius R is placed next to a long straight wire, as shown in the diagram below. The current in the straight wire points to the right and is of magnitude 3 A. see diagram...

How can I calculate how much heat a resistance wire gives off when I energize it? For example, I have calculated the wattage per square inch of a heating element I plan on building. How do I know how much actual heat it will give off? Thanks.

Homework Statement A rectangular loop of wire with dimensions 2.32 by 7.91 and resistance 0.557 is being pulled to the right out of a region of uniform magnetic field. The magnetic field has magnitude 3.01 and is directed into the plane of the following figure . At the instant when the...

Homework Statement A circular coil has 25 turns and a radius of 5 cm. It is at the equator, where the earth’s magnetic field is 0.7G north. Find the magnetic flux through the coil when its plane is (a) horizontal, (b) vertical with its axis pointing north, (c) vertical with its axis pointing...

Homework Statement http://i.imgur.com/2WKCR.jpg Homework Equations Potentially: L(final) = L[1 + tau/(YA) + alpha(T - To)] The Attempt at a Solution Frankly I have no idea where to begin.

Homework Statement What is the force acting on a magnetic dipole that falls through a loop of wire? Any sort of answer, exact, approximate or a reference to a source that covers this would be excellent. I haven't been able to find much of anything on this problem. Homework Equations The...

Homework Statement https://fbcdn-sphotos-a.akamaihd.net/hphotos-ak-prn1/553004_1959186995753_1725123128_934768_456680196_n.jpg In case the words are too small: I2= 6.61I1 The net magnetic field at center of loop is 0. I'm looking for the radius of the loop Homework Equations for...

Homework Statement a wire carrying a current of 3.2A has a radius of 1.2mm. the material of the wire has 2.5x10^25 free electrons per cubic metre. the elementary charge is 1.6x10^-19 Homework Equations I=Anev cross section = pi*r^2 The Attempt at a Solution pi*0.0012^2 =...

12-gauge copper wire has a radius of 1.03×10−3 m. (a) What is the resistance of 11.5 m of this wire at 20°C. (b) How much current will pass through the wire if a potential difference of 9.00 V is applied across it? The resistivity for copper is 1.7E-8 ohm meters For part a: The equation is...

You have a fine wire with a cross sectional area of 9.4×10−10 m2 and a length of 1.1 m. You wish to determine what it is made out of, so you connect it to a standard AA battery (1.5 V) and measure a current of 0.048 A. What material is the wire most likely made out of? The options for the...

Homework Statement A long wire carrying 100 A is perpendicular to the magnetic field lines of a uniform magnetic field of magnitude 5.0 mT. At what distance from the wire is the net magnetic field equal to zero? Homework Equations B = iμo/2∏R The Attempt at a Solution I...

If I had a current carrying wire in an E field. Would it deflect? The wire it self just has a B field and no free charge. But If I was moving with respect to the wire I would see length contraction and a net E field. So in my frame the wire would deflect. Or is something wrong with my reasoning?

hi guys.. I'm new here and this is my first post.. my friends told me that the title of this post is impossible and i need a car battery to heat the 800W nichrome wire, and i believe them.. they also said that AC will solve the problem.. but i need to use DC so i came up with using diodes.. the...

Homework Statement The current in a wire consists of n electrons per unit volume moving with a velocity v. What is the effect on these electrons of the magnetic field set up by the current itself within the wire? What is the force on one electron at a distance r from the centre of the wire...

I quote from my book: "Just after the switch is closed, the inductor acts to oppose a change in the current through it." "Because the current through each inductor is zero before the switch is closed, it will also be zero just afterward. Thus, immediately after the switch is closed, the...

hello, i am a final year student doing electronics engineering. For my final year report i made the mistake of choosing steer by wire as a project which i really can't handle. However, i am expected just to touch the subject just on the surface. It really is a very hard topic for my level...

Say I have a solenoid that has a magnetic field Bo Sin(ωt) passing through its axis. What will be the EMF induced in the solenoid as a result ? I know it'll be a function of Cos (ωt) but I am more interested in how my choice of the solenoid will affect the EMF that I'll ultimately measure...

Homework Statement A straight wire, of current I, radius a is centred at (α,β). What are the x and y components of the magnetic field B inside one of the wires? Homework Equations ∮B.dl = μ I_enc ∫∫J.dS = I The Attempt at a Solution Any point (x,y) in the wire has a constant...

Homework Statement A solid cylindrical conducting shell of inner radius a = 5.3 cm and outer radius b = 7.9 cm has its axis aligned with the z-axis as shown. It carries a uniformly distributed current I2 = 7.1 A in the positive z-direction. An infinite conducting wire is located along the...

Homework Statement The problem is shown in the link below: http://postimage.org/image/do2b7xz0b/ Homework Equations Biot-Savart Law's and dF=Idl x B The Attempt at a Solution My attempt is really just a mess. I essentially want to break it up into 2 segments. (1) Being the...

I need to make a 1 metre long heating element from NiChrome Wire. The wire I have is 0.9mm with resistance of 1.7ohms per metre. Can I wire it straight to the mains with a light dimmer switch in place to limit the power?

Homework Statement An infinite straight wire carries a current I that varies with time as shown above. It increases from 0 at t = 0 to a maximum value I1 = 2.1 A at t = t1 = 14 s, remains constant at this value until t = t2 when it decreases linearly to a value I4 = -2.1 A at t = t4 = 24 s...

Homework Statement Is the magnetic field around a point in a current-carrying wire radially outward (spherically) like the electric field? Or is it a bunch of concentric circles extending in one plane? I've always thought of it as a bunch of concentric loops in the same plane, however...

Homework Statement A 10.0 cm long hollow nichrome tube of inner diameter 2.20 mm , outer diameter 5.10 mm is connected to a 2.50 V battery. What is the current in the tube? Homework Equations V=IR R = p*(L/A);p = resistivity of nichrome (1.5E-6), L = length of wire, A = Surface area of...

Hello everyone. I'm trying to do a homework in digital integrated electronics class and feel like I can finish it only if I had a good set of notes. I have problems like comparing the input capacitance of a Mosfet to a wire of certain length, getting RC time loss in a wire, power...

Homework Statement A hollow copper wire with an inner diameter of 1.4 mm and an outer diameter of 2.6 mm carries a current of 2.50 amps. Copper has an electron density of 8.5x1028 m-3 and a conductivity of 6.0x107 (ohm m)-1. a. What is the electron drift speed in the wire? b. What is the...