What is Wire: Definition and 1000 Discussions

A wire is a single usually cylindrical, flexible strand or rod of metal. Wires are used to bear mechanical loads or electricity and telecommunications signals. Wire is commonly formed by drawing the metal through a hole in a die or draw plate. Wire gauges come in various standard sizes, as expressed in terms of a gauge number. The term 'wire' is also used more loosely to refer to a bundle of such strands, as in "multistranded wire", which is more correctly termed a wire rope in mechanics, or a cable in electricity.
Wire comes in solid core, stranded, or braided forms. Although usually circular in cross-section, wire can be made in square, hexagonal, flattened rectangular, or other cross-sections, either for decorative purposes, or for technical purposes such as high-efficiency voice coils in loudspeakers. Edge-wound coil springs, such as the Slinky toy, are made of special flattened wire.

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  1. Adeel Ahmad

    Magnetic Field in a Semi-Infinite Wire

    Homework Statement Homework Equations B = μi / 4πR is the equation for a semi-infinite straight wire The Attempt at a Solution I know that for each situation in a,b, and c I would use the equation I listed above, but I am not sure what I would plug in for R for each situation.
  2. A

    Bead sliding on a wire - calculus of variations

    I am asked to find the shape of a wire that will maximize the speed a sliding bead when it reaches the end point(Similar to the brachistochrone problem expect that the speed is to be maximized and not time minimized). But shouldn't the speed at the end be independent of the shape of the wire...
  3. William123

    Wire gauge on a simple speaker

    Hey I've built a speaker and the cone is about 20cm in diameter. I need help choosing the wire gauge for the voice coil though. When I look at this chart http://www.powerstream.com/Wire_Size.htm I can't really see anything that will work. My stereo puts out 50W and if I want the resistance to be...
  4. gsmtiger18

    Displacement current and magnetic flux through a wire loop

    Homework Statement A long straight wire has a line charge, λ that varies in time according to: λ = λ0e(-βt). A square loop of dimension, a, is adjacent to the wire (at a distance a away from the wire). Calculate expressions for the displacement current at the center of the wire loop and the...
  5. S

    Biot-Savart's Law for cylindrical conductor

    Homework Statement The figure shows a cross section across a diameter of a long cylindrical conductor of radius a = 2.92 cm carrying uniform current 151 A. What is the magnitude of the current's magnetic field at the center of the conductor? Homework Equations Biot-Savart's Law The Attempt...
  6. S

    How Does Biot-Savart Law Calculate Magnetic Field at Point P?

    Homework Statement The figure shows two very long straight wires (in cross section) that each carry a current of 3.19 A directly out of the page. Distance d1 = 6.00 m and distance d2 = 4.00 m. What is the magnitude of the net magnetic field at point P, which lies on a perpendicular bisector to...
  7. bburke95

    Find Electron Current Through Iron Wire

    Homework Statement What electron current is driven through a 1.4-mm-diameter iron wire by a 0.070 V/m electric field? The mean time between collisions in iron is 5.2×10^−15s . A=1.5*10^-6 m^2 ne=8.5*10^28 m^-3 Homework Equations I know I need to use ie = neAVd, but I'm having trouble finding...
  8. P

    I Magnetic Attraction: Exploring E&M Wire Interactions

    Apologies if this is being posted in the wrong section! this is just a side thought I came across, it is not HW. In learning about magnetism, I know that a changing current in a wire creates a magnetic field. So why are wires in our homes/ anything with wires close together not constantly...
  9. DavideGenoa

    I Uniform current in cylinder and straight wire: same field?

    Hello, friends! The tridimensional version of the Biot-Savart law says that the magnetic field generated at the point ##\boldsymbol{r}\in\mathbb{R}^3## by a tridimensional distribution of current defined by the current density ##\boldsymbol{J}##...
  10. D

    Young's Modulus Question: stretch of a wire

    Homework Statement A force stretches a wire by 2mm. A second wire of the same material and with the same area of cross-section and twice the length is also stretched by the same force. What will its stretch be? Homework Equations F= (YA/L)ΔL The Attempt at a Solution F, Y, and A are all...
  11. ing_it

    Intensity of an electric field near a wire -- With and without Gauss' Law

    Homework Statement We have a wire of the length L=0.2m which is uniformly charged with a linear density of Lambda = 3nC/cm. Find the intensity (E) of the electric field in point A1 whose perpendicular distance from the wire is a=0.05m. The wire is in a vacuum. Compare the intensity with the...
  12. A

    EMF about a loop moving toward a wire with current

    Homework Statement A picture of a related problem is attached below. My problem is the same, except that v is toward the wire, not away from it. I, r, v, b and a are given. "Find the emf about the loop without assuming that B changes at any point" My problem is that this question isn't...
  13. ezioauditore

    Sag in wire due to a weight (given the Young's modulus)

    Homework Statement A mild steel wire of length 1 m and cross-sectional area 0.5*10^-2 cm^2 is stretched within elastic limit horizontally between two pillars.A mass of 100 g is suspended from mid-point.Depression at mid-point? Homework Equations Sag in metal rod is=WL^3/(4BD^3Y) where...
  14. C

    Two coils of wire with the same size and shape

    Homework Statement Two coils of wire that have same shape and dimensions are thickly rolled up so that the coincide, they only differ in number of coils (windings) N1 for the firs one and N2 for the second one (N1<N2). When there's constant current in the first one and there's no current in the...
  15. Toughnuke

    Electromotive force (EMF) of a circular loop wire

    Hi, so, I got help from this homework problem by posting it on chegg, but I want clarification. A circular loop of wire of radius 12.0 cm is placed in a magnetic field directed perpendicular to the plane of the loop and into the page. The field is decreasing at a constant rate of 0.050 T per...
  16. R

    Calculating Magnetic Field at a Point Near a Long Wire

    Homework Statement Calculate the magnitude of the magnetic field at a point 100cm from a long, thin conductor carrying a current of 1A. Homework Equations B = ui/2pi(a) The Attempt at a Solution My question is why is this modeled after a problem with an infinite wire? When I first read it I...
  17. DrPapper

    Vector Potential: Infinite Wire and Infinite Solenoid

    Homework Statement Homework Equations Provided in the questions I believe. Here's the triangle from question two. The Attempt at a Solution QUESTION SET 1 TOP OF PICTURE A.) I didn't know how to just "guess" what the constant should be so I actually worked it out. I found the constant...
  18. P

    How to wire a Lithium Battery Pack Q

    hi all, i am embarking on a new project, building a outdoor rolling credenza that has TV (with air operated TV lift), cd player, small receiver, 100% wireless (power and wifi, etc). my design calls for a battery pack that can deliver approx 5x106 joules, this leaves me in the ballpark of...
  19. PupuWire

    Can copper be harvested from discarded phone wire?

    I have approximately 30 pounds of discarded phone wire. I would like to recycle the metals (copper?) within, but don't know if it is feasible or even worth attempting. I also just returned from helping a parent clean out the garage, including a retired aerospace engineer's vast collection of...
  20. TheSodesa

    Mutual inductance of a long wire and a triangular loop?

    I originally posted this to the advanced homework -section, but maybe this isn't advanced enough to warrant being posted there :oops:. If a mod sees this, feel free to delete the original on the other forum. I'd do it myself, but I can't. 1. Homework Statement Calculate the mutual inductance for...
  21. Z

    How Does the Angle Between Wires in a Magnetic Field Affect the Force on Them?

    Homework Statement Two wires AD and DC are put in the magnetic field with induction B=0.01T so that they form the angle pi/3 radian and the extremities A and C are in the same force line (what does it mean?). In the wires passes the current I=2A (intensity). Find the forces with which the field...
  22. PhiowPhi

    High current in a supercooled wire?

    I'm trying to understand heat-transferring process and the maximum amount of current and coolant required to apply and maintain(for a short-duration) high current in a certain conductor, before I start considering an experiment, I'd rather have my work correct in-terms of the calculations and...
  23. S

    Homework help -- magnetic field from a wire causing compass deflection....

    Homework Statement A current 2A flows in a wire. Value of horizontal component of Earth magnetic field in the region is 2x10^-5T. Small compass placed 5cm due north of the wire. Calculate the angle through which the needle deflects due to the current flowing in the wire. Assume u0= 4pi x 10^-7...
  24. Titan97

    Heat generated due to motion of wire in magnetic field

    Homework Statement A wire is moved with constant velocity such that the motion is perpendicular to the length of the wire in a region containing magnetic field perpendicular to the plane of motion. The wire has a resistance R. Will thermel energy be generated in the wire? Homework Equations...
  25. PhiowPhi

    I A strong field from a wire placed in an exterior B

    When a current carrying wire is placed in an exterior magnetic field, it's known that there is a Lorentz force, and when calculating the magnitude of the Lorentz force, the magnetic field of the wire is never considered. What if the wire's magnetic field is stronger by a huge factor to the...
  26. K

    Cylinder wrapped with wire on hill with magnetic field

    Homework Statement The figure shows a cylinder of mass 3.5kg, radius 4.4cm and length 10.2cm with 105turns of wire wrapped around it lengthwise, so that the plane of the wire loop contains the axis of the cylinder. What is the least current which while flowing through the loop will prevent the...
  27. Z

    Find the induction of the magnetic field at the point O

    Homework Statement In a wire passes the current I=21A. A part of the wire is bent to form three consecutive sides of a square with sides 40 cm. Find the induction of the magnetic field in the point O which is the center of the square. Homework Equations B=I*μ0*/2*pi*d The Attempt at a Solution...
  28. Z

    Find the force that the magnetic field applies on the wire

    Homework Statement Find the force that the magnetic field with B=10^-2 T applies on the wire with length 20 cm when it forms with the force the angle 30 grades when in it passes the intensity 5A. Homework Equations F=B*I(intensity)*l(length)*sin alpha The Attempt at a Solution...
  29. E

    Calculating Tension and Net Force in Suspended Cable System

    Homework Statement A 50.0 kg 6.00m awning is held up by a wire in the middle. A 15kg sign hangs at the end. Calculate the tension in the massless wire and the magnitude of the net force from the wall acting on the awning. The cable forms a 40 degree angle with the awning at the bottom right...
  30. Z

    Find the force between two wires

    Homework Statement Two rectilinear wires with length 100 m have the intensity 2 A. The wires in are perpendicular directions with distance 5 meters from each-other. Find the force they interact. Homework Equations F=(I1*I2*μ0*l)/(2*pi*d) The Attempt at a Solution...
  31. R

    Force of a wire induced by earth magnetic field

    Homework Statement The power cable for an electric trolley (see figure) carries a horizontal current of 330 A toward the east. The Earth's magnetic field has a strength 5.0 ✕ 10-5 T and makes an angle of dip of24° at this location. Calculate the magnitude and direction of the magnetic force on...
  32. U

    Current required to lift a wire in a magnetic field

    Homework Statement A wire of mass 3.0g and length 60cm is placed on a table parallel to the East-West direction. If a current flows through the wire from West to East, how large must the current be to cause the wire to lift off the surface of the table? (The Earth's magnetic field has strength...
  33. T

    Calculate the required current flow in the suspended wire

    Homework Statement In the figure, the top wire is 1.5 mm diameter copper wire and is suspended in air due to the two magnetic forces from the bottom two wires. The current flow through the two bottom wires is 70 A in each. Calculate the required current flow in the suspended wire. Homework...
  34. LotusTK

    How do the magnetic fields of a magnet and a wire interact?

    Im not too sure about the (ii) part of this question. The mark scheme is very poor too and gives very little information (which is always the bloody case with A level mark schemes). I don't know what i can say about how the two fields interact. Can someone tell me what i am missing in my...
  35. A

    Calculate the rise in temp in copper 3 core wire

    Dear Guys, It will be really helpful if some one can give me the calculation step by step or some calculator where in I can resolve my long pending problem. Thanks in advance I will be really glad to have a correct answer. The Q is below Calculate temperature rise in 3 core cable after 3 hrs...
  36. C

    Finding electric field of a wire within a cylinder

    Homework Statement [/B] A wire with linear charge density lambda is surrounded by a cylindrical conducting shell with radius r and surface charge density sigma. Find an expression for the electric field (magnitude and direction) as a function of distance d from the wire, on an axis...
  37. Dewgale

    Magnetic Field due to a curved wire

    Homework Statement A very long straight wire carries current I. In the middle of the wire a right-angle bbend is made. The bend forms an arc of a circle of radius r, as shown in the figure below. Determine the magnetic field at the center of the arc. Homework Equations Biot-Savart Law: ##dB...
  38. J

    Number of wire turns to make a Magnet Generator

    I'm trying to make my own simple magnet generator project Like these: http://amasci.com/amateur/coilgen.html http://www.wikihow.com/Make-a-Simple-Electric-Generator with the following materials: 2 1.5X1.5X1/8" square magnets https://www.amazon.com/gp/product/B011FNB7WK/?tag=pfamazon01-20...
  39. P

    Find the resistance of a wire (conductor)

    Homework Statement If the diameter of a wire (conductor) is dimidiated , then its resistance: A Remains unchangable B is diminiated C Becomes two times greater D Becomes 4 times greater Homework Equations R=constant*length/Surface The Attempt at a Solution Cross sectional area=pi r^2=pi...
  40. P

    The resistance of a wire (conductor) in cylindrical form is:

    Homework Statement The resistance of a wire (conductor) in cylindrical form is: A Disproportional with the length of the wire (conductor) B Disproportional with the square of the wire (conductor) section C Proportional with the square of the length of the wire (conductor) D Proportional with...
  41. A

    What is the self inductance of a circular loop of wire?

    If current I passes through a circular loop of radius R,then what will be the self inductance of that loop? (calculating flux through the loop leads to calculating magnetic field at every point inside the loop which is an elliptic integral.)
  42. S

    Nichrome wire overheating failure in standard air heater

    Am experimenting with an Omega Engineering AHP 7561 standard air heater rated for up to 240v. Specs include ability to keep a 20 cfm flow exiting @1000F while pulling about 10A @220v. Nichrome melts around 2400F. I'd like to produce small bursts (lasting a few seconds) of very hot air, like...
  43. A

    Electric field due to a current carrying wire

    Homework Statement Circular loop of diameter d located in the vertical plane (x-y) at a distance h from the perfectly conducting half-space. The current source creates a time-harmonic current i(t)=Acos (ωt). Find the radiated electric field vector in the plane (x-y) in the far zone of the...
  44. S

    Circulation of a Mag field around a wire, what is the angle?

    Circulation of a magnetic field = closed loop integral ∫c B ⋅dl = μ0I B is mag field strength, dl is small line element, I is current Im imagining both B and dl point in the same direction from the diagram. So the dot product here, I picture as cosθ = cos0 Is that correct way to...
  45. kostoglotov

    Marginal inductance and capacitance of a real wire?

    Speaking just of long straight wires, not loops, coils or solenoids. Ideal wires have no resistance. Of course they would have no capacitance. And real wires have some very small amount of inductance, no? Firstly, would an ideal wire have some ideal nonzero inductance? Why/why not? After all...
  46. B

    Electrical length of wire wound on magnetic core?

    Hi everyone, I read somewhere that when a coil is wound on a magnetic core it's electrical length becomes longer than it's physical length. I remember seeing this formula L=l * sqrt Ue Where L= Electrical length l=actual (physical) length Ue=Core permeability Does anyone know if this is...
  47. A

    Frequency of a bead on a parabolic wire

    Homework Statement Calculate the frequency of a bead with a mass of m vibrating on a parabolic track equals to y=Ax2 Homework Equations F=ma The Attempt at a Solution Looking at the bead at any point which isn't equilibrium, I have: 1. may =N-mgcosθ 2. max=mgsinθ I tried to look at a...
  48. T

    Finding current and temperature of platinum wire

    I plan on using a 1 ft long, 0.005" diameter platinum wire as part of an electrode. The wire will be bare but will be inside a hollow plastic tube that has an inner diameter of 0.08". It needs to be able to carry a maximum of 1 mA for a length of 10 minutes, while not exceeding 60oC. I'm not...
  49. D

    How to Calculate the Current Flowing Through a Gold Wire?

    Homework Statement The terminals of a 0.70 Vwatch battery are connected by a 70.0-m-long gold wire with a diameter of 0.100 mm. What is the current in the wire? Homework Equations V = IR R = pL/a The Attempt at a Solution I try to find resistance first, resistivity of gold is 2.2 * 10 ^-8...
  50. WiseGreatTrixie

    Copper wire problems and strange phenomenon

    ok so I was creating a connection today and used a 5 v led on a 1.5 v battery. Battery was in a case from radioshack and had insulated leads, full of twisted micro wire. Since there was no way to crimp it or strip the wire without me ruining the twists, I just bundled it to some non twisted wire...
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