Wire Definition and 1000 Threads

When we have a current in a long wire, what is the kind of total energy of the system? We do have an electric field inside the wire and a magnetic field outside it. I think the electric field has an energy, say E, and it is only this energy which appears also as magnetic energy and we don't have...

Homework Statement a 8kg ball is hanging from a 1.35m string. A 2 kg ball moving horizontally at 5m/s hits the hanging 8kg ball in an elastic collision. What is the tension in the string just after the collision? Homework Equations The Attempt at a Solution Initially there is only...

There is a battery connected to a non ideal circular conductor wire. What is the specific mechanism by which one electron inside the wire “feel” the presence of the battery because of electric field?

Does a current carrying wire create an electric field in it's vicinity? I believe that there is no electric field created around the wire(ideal situation). That's because the current carrying wire is neutral. You can imagine electrons moving in a specific direction under the influence of the...

Homework Statement Suppose that the magnetic eld in some region has the form B = kzx(hat). (where k is a constant). Find the force on a square loop (side a), lying in the yz plane and centered at the origin, if it carries a current I, flowing counterclockwise, when you look down the x axis...

Homework Statement A 2.0 cm length of wire centered on the origin caries a 20 A current directed in the positive y direction. Determine the magnetic field at the point x = 5.0 m on the x-axis. Homework Equations B = uI/2piR The Attempt at a Solution Using the equation above I just...

Homework Statement Find the center of mass of a semicircular wire. The wire is a semicircle, but the important thing to realize is that the wire is a closed loop. Think of a solid half disk, and just take the outer edge. Where is the center of mass? This will be positioned with the center at...

Does the ground wire used in transmission/distribution systems also serve as a neutral wire in some cases or is it used only to protect the conductors against lightning strikes?

Homework Statement Find the magnetic field 4.0 cm from a very long, straight wire that carries a current of 17.0 A. Homework Equations I don't know what equation to use The Attempt at a Solution I tried to find the equation for this question

Hi, how can we reduce field at a point(of observation) 30mm from a 10 m long blank copper wire with return path somewhere at infinity carrying DC current by using a 1m long copper tube 1mm wall thickness and 30mm outer diameter?

Cirquit homework Homework Statement A wire hangs loosely in a magnetic field, it is free to move up or down, the field is 90° on the wire. So the wire gets a charge of 2C over a period of time that is not stated. find the distance it moves during this time. Wire has length 0,25cm, mass m...

Homework Statement If we connect the neutral and Earth wires wrongly in the plug, can the appliance still work? Homework Equations The Attempt at a Solution I am not too sure, but my answer is probably no. The circuit cannot be completed, as the current will flow to the ground...

Hi, I am modeling the Unshielded Twisted Pair Wire and I have hit a roadblock there. I have studied the mathematical equations for the twisted wire pair. And they give results with an accuracy of 10%. This is in part due to the fact, that almost all equations assume that both the wires are...

Homework Statement A long straight wire of circular cross section with radius R carries current I and is immersed in a large volume of water. The wire is non-magnetic. Calculate the magnetization M(r) in the water which has a susceptibility χm. What is the bound current density Jb(r) for s...

1. Problem statement. 2. Known equations Amperes law, biot-savart law 3. Attempt. Just taking steps 1 at a time, I first drew a diagram then I found Jo in terms of I and R, and since it is a non uniform current I know that to find the current I use J = I / A substitute A for 2(pi)rdr, and...

There is a wire oriented in the z direction with no current in it for t<0. At t=0, there is a burst of current: I(t) = qδ(t). What is the vector potential \vec{A}? (\vec{B}=∇×\vec{A}) My solution: let point P be located distance s from the wire, z be length along wire, and Ω be distance...

Hello! My first post at Physics Forums! Nice to meet you! In an electromagnet, where the coil windings are not touching themselves (the coil is not touching itself), is there any difference on the magnet strength created depending on whether the wire is insulated or not (bare wire)? If the...

I have a question. When an energized wire contacts a ground wire or goes to ground, I know there's an increase in current and the breaker will trip, but my question is why? Is the energized conductor pulling more electrons from the Earth causing it to exceed the breaker rating? Thanks

1. Problem statement The current density from the axis in the wire of radius R is given by J = cr3/2 A) draw the current density as a function of r graph B) determine the constant c in terms of Itotal C) determine the current as a function of r. D) draw the graph of the current as a function...

Homework Statement A straight wire segment of length L makes an angle of 21.0 degrees with respect to the x axis. The wire carries a current of 4.10 A in the direction shown in the figure. There is a magnetic field in the vicinity of the wire which points in the negative z direction with a...

A uniform horizontal wire with a linear mass density of 0.520 g/m carries a 2.70 A current. It is placed in a constant magnetic field, with a strength of 4.17×10-3 T, that is horizontal and perpendicular to the wire. As the wire moves upward starting from rest, what is its acceleration? Neglect...

Homework Statement Please refer to the image attached. I don't understand why can they just take 1.8m as the original length, since there is already a load hanging there. My calculations yield the value of strain to be e/L, but in the answer it is e/1.8. Please explain this to me. Homework...

If a resistor of a resistance = 6 ohms is connected to 2 wires of zero resistance (0 ohms) in a DC circuit with a battery of voltage = 12V, the current throughout is 2A. The voltage drop across a 0 ohm wire is V = R*I. Because R = 0, the voltage drop across the wire is 0V. The only way for this...

Homework Statement A particle is constrained to move without friction on a circular wire rotating with constant speed ω about a vertical diameter. Find the equilibrium position of the particle, and calculate the frequency of small oscillations around this position. Find and interpret...

Hi all! First, this is neither a part of homework, university or anything like that , it is my own wondering. I have been searching a lot for how to calculate the Lorentz force acting on a single current carrying wire in Earth´s magnetic field which is 0.6 Gauss. for say a wire of voltage...

Consider a solid cylinder of radius R. an varying current of current density δ flows through. what would be self inductance of that cylinder

Homework Statement \rho_{wire}=a, surface charge density \rho_S What is potential difference of a point a distance of b measured from the centre of the infinitely long wire, and the surface of the wire? Since all of the charge is dispersed on the surface of the conductor, there will exist no...

Hi, I am designing a plastic recycler and I need advice on choosing gauge of some nichrome wire. I want the heater to reach around 220 degrees C and I will be powering it with a laptop charger (19v 7.1 amps). Temperature control will be achieved with a PID controller. The nichrome wire will...

Hello Friends I am working on home made electromagnet and I have only volt & Ohms details like 12Volt DC, 24Volt DC & 240V AC and ohms is 80Ω, 100Ω & 120Ω for all for example 12VDC 80 ohms coil, 12VDC 100ohms,24VDC 80Ohms coil...etc. now i want to know which copper gauge we have to choose...

Lets say i have a infinitely long wire with charge per length, λ and a point, p of a position with its closest distance to the wire is y. The wire extend infinitely parallel to X-Axis. How to determine the voltage at the position p? Can i first regard the voltage contributed by a very small...

Homework Statement A long, straight wire of radius a has current density J = J0e−β(α−ρ)uz where β is a constant and ρ < α. Determine B inside and outside the wire.Homework Equations J=I/((pi)a^2) B=(μIρ)/(2(pi)(a)^2) The Attempt at a Solution Here is what I did B=(μρ/2)J0e^(-β(alpha-ρ))

I'm looking at getting a lengthy piece of wire, looping it around into either a circle or an ellipse and running a current through it to get a magnetic field, however I'm unsure what type of wire to go for? There's enamel copper wire and the standard aluminum wire. Which one will give me the...

What is the electric field due to a current carrying wire? In a Griffiths EM problem, he treats the E field outside a current-carrying wire as if it were due to a static charge distribution. Is this a valid approximation? Upon google-searching i get very vague/contradicting answers, so any...

I have a 75w 2meter mobile transceiver (Yaesu FT-2900R – 13.8 volts DC, 15 Amp max draw, min draw is .3 A-.7 A ) that I would like to use in a camp type setup. The power source will be Two 12volt batteries (not dedicated) on a small enclosed utility trailer, which will be 20’-50’ away from the...

Hi guys. I'm an architecture student who is designing a lamp that will be made up of multiple, modular pieces of plywood. Each piece will be a hexagon containing 6 LED lights (one on each side). The idea is to have a base that plugs into a socket with a wall wart: I was thinking 12 volts AC...

Over about the last decade I have encountered with increasing frequency a black corrosion on the strands of copper wire. When you strip the wire it'll be jet black instead of old copper brown. It cannot be soldered. It is a real nuisance when trying to repair something like an automobile...

When charged spheres are connected using a conducting wire, the charge will redistribute so as to make the potential constant because the connection makes them a single conductor and conductors are equipotential surfaces. My doubt was that if the spheres are of different size and have different...

The task is to calculate the force acting on a 50 meter long current-carrying wire due to Earth's magnetic field. The angle of inclination is assumed to be 70 degrees. Here's a schematic diagram: The exaggeratedly drawn wire represents a segment of a wire on a power grid. In order to find...

Need help understanding the "signal" wire. My servo, http://www.allelectronics.com/make-a-store/item/DCS-110/STANDARD-RACING-SERVO/1.html Not sure if this servo requires AC or DC power. What I really want to understand is the signal wire; specifically how changing the input value either...

How do you figure out which way is north when you're lost and the only things you've got with you is a copper wire and a voltmeter? Thanks in advance.

Homework Statement Iron atoms (atomic mass 56) contain two free electron spins that can align with an external magnetic field. An iron wire 3 cm long and 1 mm in diameter is suspended vertically and is free to rotate about its axis. A strong magnetic field parallel to the wire's axis is...

http://img42.imageshack.us/img42/6336/14vu.png please explain your answer! also if u know of similar problems or where this problem is taken from do tell me coz i have an admission exam coming up soon please explain the following: 1. what is the flux like? 3. how the coil spins? z. how is...

In the classic problem of the induced EMF in a moving conductor (as in the picture above), the calculation for the induced EMF is as follows E=\frac{d\Phi_B}{dt}=\frac{d(BA)}{dt}=\frac{Bd(A)}{dt}=\frac{Bd(Lx)}{dt}=\frac{BLdx}{dt}=BLv. The derivation assumes that the magnetic field B is...

Hello I have a problem where a wire is pulled around a half circle (disc) and then both ends pulled. The force in both ends are equal (F1 + F2). The disc must in total put up a force (F3) equal to F1 + F2 to not be pulled along by the wire. My question is how does the force of the...

Homework Statement An object of mass 0.5 kg is hung from the end of a steel wire of length 2 m and of diameter 0.5 mm. (Young's modulus = 2 x 1011 N/m2). The object is lifted through a distance h (thus allowing the wire to become slack) and is then dropped so that the wire receives a sudden...

Hi PF! I'm working on a portable heating circuit. I'd like to use an ultracapacitor charged by 2 AA batteries to increase the temperature of 2.25m of 1mm Nichrome wire by 34° in 6 seconds. The question is, what capacitance does the ultracapacitor have to have? Initial values: •...

Hello, I was thinking about induced currents in a wire(coil). For example when a current from an external source passes through a wire - the changing magnetic field induces a current opposing the current applied (back emf) like a Newton's 3 law and nothing would ever pass through a wire, but the...

Homework Statement Find an expression for the magnetic field inside a wire carrying a current density J = Cr2 where C is a constant to be determined in the problem. The total current in the wire is I and the radius of the wire is R. Your answer should be a function of r, R and I, but should not...

I try diagonalize the Hamiltonian for a 1D wire with proximity-induced superconductivity. In the case without a superconductor is all fine. However, with a superconductor I don't get the correct result for the energy spectrum of the Hamiltonian (arxiv:1302.5433) H=\eta(k)τz+Bσ_x+αkσ_yτ_z+Δτ_x...

I have two wires, each 1 meter in length. They are at a parallel distances (d) of 5cm from each other. I send a current through one wire: I1 = 2 amps, and what I want to find is the current induced on the other wire: I2 = ? I can find B with the following formula (given a radius - which I...