# 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. ### Finding the power loss in a wire of varying cross-sectional area

TL;DR Summary: Finding the power loss in a wire of varying area - my problem is I don't know how to set up the integral Hopefully you can see in the diagram below that the area of the wire varies linearly with length. I know the equations for resistance and power loss and I can express the...
2. ### I Partial derivative of wire tension relative to temperature, holding wire length constant.

I have a question about a derivation I saw in the book "Heat and Thermodynamics" by Zemansky and Dittman. A "sufficiently complete" thermodynamic description of a wire is given in terms of only three coordinates 1. tension in the wire, ##\zeta## 2. length of the wire, ##L## 3. absolute...
3. ### Electromagnetism question -- Forces between two current carrying wires

Here is the question. I just wanted to confirm and see if I'm understanding the question clearly. For 3a) I said the first wire would have the magnetic field going in a counter clock wise direction and the second wire would have a magnetic field going in a clockwise direction using the right...
4. ### Can we twist the two ends of the wire together?

Hello, We need 20 meters of 12 Gauge electrical wire but don't have 12 Gauge wire. Can we use two 6 Gauge wires and twist the two ends of the wire together? Is it harmful to electronic appliances? for example, air conditioners [Mentor Note: original question restored; the OP will post a follow...
5. ### Heating of a conductor (1000 turn coil)

Suppose I have a current carrying wire that is 20 AWG copper. There is insulation on the copper wire that is rated for 200 degrees C. I have 500 meters of the wire wound into a coil. The coil takes up a total volume of 0.0001157 meters cubed (roughly 1000 turns). Suppose I run 3 amps of current...
6. ### Optimum Battery (and Wire) to Power 10x Mini 1.5V Bulbs in Parallel?

TL;DR Summary: We purchased a 9v battery box and planned to wire it—in parallel—to 10 mini bulbs, assuming 10 bulbs drawing from the 9v would be more than enough voltage drop to not go up in smoke. We purchased a 9v battery box and planned to wire it—in a parallel circuit—to 10 mini bulbs...
7. ### Forces for bodies connected by a wire on inclined surface

Hello PhysicsForums! Here is my attempt at a solution for the problem stated above: Where m1 and m2 are the masses Where Ff1 and Ff2 are friction for each mass Where a1 and a2 is the resulting acceleration Where S is the fore of the wire (threadforce) Where FN is the normal force The answear...
8. ### Calculate Max Resistance for 2 Parallel Wires

Hi, I am not sure if I have calculated the task here correctly: Based on the drawing, I now assumed that the two resistors are connected in parallel. The total resistance can then be calculated as follows ##\frac{1}{R_T}=\frac{1}{R_1}+\frac{1}{R_2}##. Since the two wires are made of the same...
9. ### I Angular momentum associated with a current carrying circular wire

How should I calculate the angular momentum carried by a current carrying circular wire? Is it correct to consider the angular momentum of the electrons moving with drift velocity? Like ##L = n m_e v_{drift} r## where ##r## is radius of the loop, and ##n## is total number of electrons moving in...
10. ### A Force Changing With Distance (bead moving on a curved wire)

I initially tried to solve this equation using work, but was stuck in a confusing integral that didn't make sense. I am almost sure that the utilization of energy is needed to solve this equation, but I have been flustered for the past three days at solving this.
11. ### Calculating Copper Wire Gauge for Resistance Thermometer Bridge Circuit

a. The resistance thermometer bridge circuit shown in FIGURE 1 has a designed maximum temperature of 200°C, ignoring the effects of connecting wire resistance. If the connecting loop is 250 m determine the smallest gauge (swg) of copper wire which must be used if the indicated maximum...

13. ### Is the Speed of Electricity Affected by the Length of the Wire?

300 000km connect light bulb and battery. I would say 1sec is need from I turn on switch to light start lighting. This video say it is 1m/c...Is this video wrong? Do electron travels thorugh wire, if 300 000km wire is connected to bulb ,why electricitly travel through space only 1m??
14. ### What kind of wire needed to prevent overheating?

I thought the answer is (B) because thinner wire means higher resistance and smaller current so smaller power dissipated in the wire, but the answer is (A) What is my mistake? Thanks
15. ### Thin heartshaped wire - Calculate the magnetic field at the origin

Hi, So I know I am to use Biot Savarts law dB= (my_0/4pi)* (I dl x (r-r')/|r-r'|^3 where r=0 because its in origo and r'=r'_c(r'_hat). This makes (r-r')= -r'_c(r'_hat) and |r-r'|^3= r_c^3. From previous questions, I have defined dl' as the infinitesimal displacement of r'(phi) when phi' is...
16. ### B-field for a half-infinitely long wire

For this problem, The solution is However, I would like to understand how to solve this using Biot–Savart Law. So far my working is: ## \vec {dB} = \frac {\mu_0Ids\sin\theta} {4\pi r^2}## However, I'm not sure what to do about the ## r^2 ## since the wire is infinitely long. I am thinking...
17. ### Magnetic Field Due to a Curved Wire Segment

For this problem, The solution is, However, why did they not use limits of integration for the integral in red? When I solved this, I used as limits of integration. I see that is not necessary since you get the same answer either way, but is there a deeper reason? Many thanks!
18. ### Solving Current & Power in 4 & 3 Wire Circuits

My thoughts were I could use mesh current analysis to derive equations for current hence power in each case in terms of ωC and R, set the equations for real power equal to each other and solve for R. While ωC are known I opted to leave them as letters thinking this might make life easier when...
19. ### B What wires should I use for my wire chamber?

I want to make my own multi-wire chamber for school, and I wonder what kind of effect different wires will have on the efficiency. After reading many papers containing research for wire chambers, I saw that all of them did tests with wires made of gold plated tungsten wires with a diameter of...
20. ### Request a Diagram or Explanation to wire 220v-50/60hz UK 3-wire device

Planning a kitchen renovation. We've found a SIEMENS iQ700 glass downdraft extractor [model LD98WMM60B] that we'd love to use. It, of course, is only available in EUROPE. EAN code : 4242003907122 Connection rating : 300 W Fuse protection : 10 A Voltage : 220-240 V Frequency : 50; 60 Hz Plug...
21. ### EMF when a loop is pulled away from a current-carrying wire

Setting up the integral to find the flux that is giving me trouble. I know that I will have to break up this integral into 2 parts, the first part account for when the start of the loop is increasing in area, and another right when I pass the halfway mark of the loop and the area begins to...
22. ### EE: How to heat a magnet with a wire while levitating a superconductor?

Hi I'm doing my extended essay (like a research paper) for the IB and I'm having a bit of trouble with my setup and data process. The plan for my experiment goes something like this: I have a magnet wrapped in wire strapped to a battery and a superconductor in liquid nitrogen. After levitating...
23. ### Why is magnetic field B along a straight wire circular not radial?

Statement: The magnetic field around a straight wire carrying a current can be explained Relativistically by changing the inertial frame of reference to the frame of the moving electrons - i.e., a Lorentz contraction of the positive charges in the wire will give a denser concentration of the...
24. ### I Is there traction force between moving electrons & copper wire?

Common sense: walking on road, there is traction between shoes & earth. I'm wondering: same thing for electric current's electrons & copper wire?
25. ### Induced EMF due to motion of a wire perpendicular to a magnetic field

This question appeared in a university entrance exam.Basically, if magnetic flux passing through a surface of a loop changes over time ,only then e.m.f will be induced to that loop.But here only a straight line is used and there's no chance of forming any area.So by definition there's no chance...
26. ### Why is platinum wire classed as a drug precursor ?

I wanted to make a simple platinum electrode with a few cm of wire. But it is hard to get. Local (Australia) science equipment suppliers are now citing platinum wire as a drug precursor. I can't see how anyone uses platinum wire or salts as a drug to get high. I am puzzled, in any case it...
27. ### Exploring 3 Phase Wire Amperage: Understanding Ampere Rules and Calculations

If you have 3 phase power and let's say line A & B = 10 amperes line B & C = 10 amperes line C & A = 10 amperes For the single line B. Since it's in both in the first and second lines, then B can experience 10 + 10 = 20 Amperes? Or is it 15 A or still 10 Ampere? Thank you.
28. ### Finding the voltage drop along a tapered wire

The actual homework question is about finding the voltage of a tapered wire, one where the two ends are different sizes (1cm and 2cm in this case). I've been searching for an equation to do this simply by just plugging in the values I have and I came across this. Where is resistivity, h is...
29. ### B Switch-to-lightbulb wire delay

Summary: Question about expectations related to electron flow and conductivity. Here's a question I have... imagine a scientist in a lab. In front of him there's a battery (with typical red/black +/- poles). Behind him is a normal light socket. Now, between the battery and the light socket...
30. ### Connecting a new cable - different wire gauge

Hi. (not a native English speaker, so apologies in advance for inadequate techical terms) 220V AC, Europe. There is a cable with 5 wires (2.5mm2 crosssection each) that I would like to cut and make a junction box in the attic to connect another cable to it, to get another outlet. The wires are...
31. ### EMF induced in a wire loop rotating in a magnetic field

To solve this problem, we need to evaluate the following integral: $$\epsilon = \int_{P}^{C} (\vec v \times \vec B) \vec dl$$ The main problem is, in fact, how do we arrive at it! I can't see why a Electric field arises at the configuration here. The magnetic field of the rotating sphere is...
32. ### Relationship between diameter and elastic potential energy of a wire

I think the answer is that the elastic potential energy will be a 1/16th of the original value. This is my reasoning: 1) If the diameter doubles, the cross sectional area is 4 times the original value. (from A= πr2). 2) F= stress/area. Force (load is the same). If cross sectional area...

34. ### A curved wire rotating in and out of a magnetic field

If I'm correct then the maximum change in magnetic flux occurs when the semi circle crosses the point at which it's plane is parallel with the magnetic field and minimal when it crosses the point at which the magnetic flux is maximum ( perpendicular with the field). I'm having trouble writing a...
35. ### Force to apply to a loop moving away from a current-carrying wire

What I have done: (1) ##\Phi(\vec{B})=\int_{S}\vec{B}\cdot d\vec{S}=-\frac{N\mu_0 il}{2\pi}\int_{s=h}^{s=h+l}\frac{ds}{s}=-\frac{\mu_0iNl}{2\pi}\ln(\frac{h+l}{h})## so ##\mathcal{E}=-\frac{d\phi(\vec{B})}{dt}=-\frac{\mu_0iNl^2v}{2\pi h(h+l)}## so...
36. ### Magnetic field generated by an infinitely long current-carrying wire

Can someone explain how there can be a radial magnetic field? I thought the magnetic field was always tangent to the circle using the right hand rule where you wrap your fingers around the current and point your thumb in the direction of the current.
37. ### Do you know if this plug for gold wire is still selling on the market?

We are dealing with extremelly thin (radius of order in mm) wires of gold at the project i am. It is necessary to plug these wires at a copper plataform. We have think two ways to do that: To weld it, or, to buy a plug that allow us to do that. SInce to weld it is the second option, we are...
38. ### Network analyzer on a single wire

I have a NanoVNA spectrum analyzer. I took a 1 meter 12 AWG solid copper wire and soldered one end of that to the center conductor of the SMA connector and did a sweep from 10 kHz to 1 Ghz looking at reflection. I have attached a photograph of the result. My hope is that someone can tell me...
39. ### Magnets near a current carrying wire

Hi! I'm trying to understand electromagnetism. So I had a question: if we place a bar magnets on the low friction surface near vertical wire, then switch on the current, what will happen? As I been told they will align with the magnetic lines, and then nothing will happen. I also suggest that...
40. ### B Generator stator: Copper wire or copper sheets?

Inside a electric generator. To produce the most electricity catching the greatest number of electrons. Instead of spinning a magnet in front of a copper loop or spinning a copper loop between 2 magnet poles my thinking is flat copper sheets would have more surface area on a single magnetic...
41. ### What is the resistivity of a wire when voltage increases?

Divide volts by current to get resistance which is 8. Multiply both sides by 8 and sigma to get: $$\frac{1m}{8\Omega\times10^{-4}m^2} = 1250$$ But this answer seems to be way off. How did I go wrong? Thanks
42. ### Find the drift speed of electrons in a wire

We need to find each variable. ##I## is already given to us as 8 amps. The charge of an electron is 1.6 x 10^-19 coulombs. The cross sectional area will just be ##\pi(1.2∗10^−3)^2## m^2. Now we need to find the free electron density. We are given the density of of copper and can use dimensional...
43. ### I Energy flux direction in a conducting wire?

On the Internet, I have read that the energy doesn't flow in the wire, for example in a very simple electric circuit made of a battery and a closed loop. When one computes the Poynting vector ##\vec S \propto \vec E \times \vec B##, one gets that its direction is towards the center of the wire...

Hi, I need to calculate the temperature of a wire, due electric current passing through, and I have no idea how to do that. I need it for a device that I want assemble. I'm using one single thread (strand) of speaker cable, like you can see in this picture: Again, Just a single thread that...
45. ### Potential due to a finite charged wire

Considering a reference frame with ##x=0## at the leftmost point I have for the leftmost piece of wire: ##\int_{x=0}^{x=2R}\frac{\lambda dx}{4\pi\varepsilon_0 (3R-x)}=\frac{\lambda ln(3)}{4\pi\varepsilon_0}##. The potential at O due to the semicircular piece of wire at the center is...
46. ### Is electrocution possible from touching a conducting wire?

why would the current flow through a person when it is already flowing through a copper conductor that is connecting the terminals.
47. ### B Grain direction for maximum tear resistance for a wire bound book

Paper has a grain direction – the direction of the long fibres. For several reasons, publishers always print hardcover books with the grain of the paper in the same direction as the fold. I'm working on a book that will be 2:1 wire bound (two holes to the inch). I was wondering what the grain...
48. ### How to wire a house using 3 phase

We are getting 3 phase power delivered to our property via our own dedicated transformer. We want to rewire the house and other buildings so that we can use different appliances on different phases. We have 4 air conditioners, 3 hot water units and the usual assortment of things you would find...
49. ### Does wire length difference create phase shift?

When wiring a 240 volt AC circuit, I've always assumed that it's important for L1 and L2 wires to be the exact same length, in order to avoid introducing a phase shift that would reduce peak voltage. Length differences can accumulate when the wires enter a panel and need to go slightly...
50. ### Trajectory of an electron traveling near a current-carrying wire

B equals 50*10^-7 T (at first instance) Fm equals 8*10^-20 N (at first instance) I know Fm is perpendicular to the velocity, and I know the estimation of the trajectory (somewhat similar to the curve y=lnx). Since I think vertical velocity will be constant, only changing the x component, I...