# What is Wire coil: Definition and 12 Discussions

Concertina wire or Dannert wire is a type of barbed wire or razor wire that is formed in large coils which can be expanded like a concertina (a small hand-held bellows-type instrument in the same family as the accordion). In conjunction with plain barbed wire (and/or razor wire/tape) and steel pickets, it is most often used to form military-style wire obstacles. It is also used in non-military settings, such as when used in prison barriers, detention camps, riot control, or at international borders.
During World War I, soldiers manufactured concertina wire themselves, using ordinary barbed wire. Today, it is factory made.

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1. ### Need help with permeability of free space.

Homework Statement In a lab that I did in Physics we calculated the magnetic field of a solenoid while constantly increasing the number of time the wire was wrapped around the electromagnet. After I obtained all the values, plotted it in a graph and found the line of best fit, the slope came...
2. ### Calculate length of wire needed for solenoid

Hi, I'm trying to calculate the length of wire that I need to wound a coil using a spool and wire of known dimensions. I was trying to use this converter but I'm not getting good results: http://www.had2know.com/technology/solenoid-coil-wire-calculator.html For instance: with a wire radius of...
3. ### Why Is the Cross Sectional Area of a Coil Used in Calculating Flux Linkage?

Flux linkage in a wire coil is given by BANcos(theta) with B being flux density, N being the number of turns in a coil and A being the cross sectional area of the coil and theta being the angle between the normal to the plane of the coil and the magnetic field. Is anybody able to explain why it...
4. ### Wire coil in decreasing magnetic field

Homework Statement A wire coil of 2 cm with 10 turns is in a magnetic field of 2 T. The field is perpendicular to the plane of each turn of the coil. The coil is wired in series with resistor of 5 Ω. The field drops at a constant rate to 0.0 T in 10 ms. What is the current through the resistor...
5. ### Practical application; wire coil dripping.

As part of a wire manufacturing process, heavy wire coils are being sprayed with oil to prevent corrosion. Final step is to have these coils dripped to eliminate oil excess. Basic question is; if I where to build a vibration platform/table to do this dripping, what would be a good consideration...
6. ### Linear movement detector using magnetic, wire coil and transistors

Hello, I have cool idea for a device and one hardest part of it is to detect the movement of the object. I think I can use a wire coil, and a small magnet attached to the moving object. When the object passes the wire coil (up or down), there will be small voltage inside the wire coil. It...
7. ### What Is the Hamiltonian for a Wire Coil Under Reflection Transformation?

When applying Noether's theorem to a coil of wire under reflection transformation invariance, what Hamiltonian would one use as as the extermized function? I realize that electromagnetism is not invariant over reflection transformations, that's what I am trying to prove.
8. ### Creating emf with a wire coil and magnet

Homework Statement We have seen this week that there are 3 ways to generate an emf (voltage or a current) using Faraday's law. Suppose you have a permanent magnet (of your choice), and 5-cm radius coil of wire with 100 loops, and a sledge hammer. Describe the three different ways the loop of...
9. ### How can I transmit a static frequency through a copper wire coil

I am trying to figure out how to program a 528 hz signal to emit and amplify through a copper wire coil
10. ### Magnetic Flux Through a Wire Coil

Hi, This problem confused me the first time around, but I think I've got it. I just want a confirmation that my reasoning is correct. I know I have the correct answer, but what is important is the method of arriving at it. Homework Statement A wire is being wound around a rotating wooden...
11. ### Engineering Help: Find the Integral for a Wire Coil

i am looking for an equation (integral) , so that i can predict what width to make a coil of wire , of certain length ,and thickness, so that it comes out to an outer diameter of 1.5" with an inner diameter of .5".. i usually spend my time in the engineering section , but i thought that i would...
12. ### Calculating Induced EMF in a Changing Magnetic Field

Ok, so here's the problem: Induced EMF A 5.80 cm diameter wire coil is initially oriented so that its plane is perpendicular to a magnetic field of 0.770 T pointing up. During the course of 0.140 s, the field is changed to one of 0.240 T pointing down. What is the average induced emf in the...