What is Coaxial: Definition and 188 Discussions

In geometry, coaxial means that two or more three-dimensional linear forms share a common axis. Thus, it is concentric in three-dimensional, linear forms.
A coaxial cable, as a common example, is a three-dimensional linear structure. It has a wire conductor in the centre (D), a circumferential outer conductor (B), and an insulating medium called the dielectric (C) separating these two conductors. The outer conductor is usually sheathed in a protective PVC outer jacket (A). All these have a common axis.
The dimension and material of the conductors and insulation determine the cable's characteristic impedance and attenuation at various frequencies.
In loudspeaker design, coaxial speakers are a loudspeaker system in which the individual driver units radiate sound from the same point or axis.
A coaxial weapon mount places two weapons on [roughly] the same axis – as the weapons are usually side-by-side or one on top of the other, they are technically par-axial rather than coaxial, however the distances involved mean that they are effectively coaxial as far as the operator is concerned.

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  1. A

    Coaxial Cylinder-Aharonov-Bohm effect

    Hi Everyone, I'm trying to find the eigenfunctions and eigenvalues for a quantum spinless particle within two concentric cylinders of radius \rho_a and \rho_b , where \rho_a is less than\rho_b, with Dirichlet boundary conditions at these two radii. It's clear to me what the solution is for...
  2. H

    Can Coaxial Wires be Converted to DC for LED Power?

    Hi Guys, For my design project, I am dealing with a horn antenna that has coaxial wire for the input and output. The problem is, I need to take the signal recived from the antenna by the coaxil and feed it to another circuit, since I need to us a circuit to down convert the freqeuncy or...
  3. B

    Charge inside and outside coaxial cable

    I'm attempting to teach myself some electrostatics, so that I'll be prepared when I head back to school full time. Homework Statement Determine the electric field inside the inner conductor, between the conductors, and outside the conductors of a coaxial cable when the inner conductor is...
  4. S

    Mixng problem of two coaxial flows

    Mixng problem of two coaxial flows... Homework Statement In the figure,an incompressible fluid ,velocity v is discharging from a 2D channel,height 2c into another 2D channel of height 2a. (a>c),their axes are common.pressure is uniform everywhere and v,w are uniform at the inlet. Inner...
  5. D

    Resonant Frequencies of Coaxial Cylinders

    Does anyone know of a formula for determining the various resonant frequencies of 2 coaxial cylinders with radius a and b and height h? Thanks.
  6. C

    Coaxial Speed of Propagation

    I know my impedance minima and their associated frequencies for a particular coaxial cable. How would I go about deriving an equation that will let me calculate the speed of propagation and the dielectric constant? My only hint is to consider the case for which Z = 0 but I don't know where to...
  7. D

    Magnetic and electric field between current carrying coaxial cables

    Homework Statement Two long concentric, cylindrical conductors of radii a and b (a<b), are maintained with a potential difference V and carry equal but opposite currents I. An electron, with velocity u parallel to the axis, enters the evacuated region between the conductors and travels...
  8. L

    Electric Field of Coaxial Cable

    http://img154.imageshack.us/img154/165/integrallll.jpg After working it out myself, I have the logarithim part equal to: [ln b - lna] + [ln c - ln b] = [ln b/a + ln c/b] = ln c/a (Not sure about this statement!) I don't understand where the c^2 and ab came from with this integral...
  9. T

    Heat exchanger consisting of Coaxial Cables

    Homework Statement A heat exchanger consists of two straight co-axial tubes, each of square cross-section. Liquid 1 enters at a rate m1 kg.s-1 at one end (x = 0) of the exchanger at temperature T10, and flows through the inner tube. Liquid 2 emerges at a rate m2 kg.s-1 at x = 0 at...
  10. I

    AC Voltage applied to coaxial cable

    Homework Statement A coaxial cable consists of two long, concentric, perfect conductors. The inner conductor is a right circular cylinder of radius a, while the outer conductor is a thin, hollow annular cylinder of inner radius b. Suppose a half-infinite length of such a coaxial cable...
  11. S

    Electric field and potential difference in coaxial cable

    Consider a coaxial cable with inner radius a and outer radius b. The potential difference between the inner and outer conducter is V. How can it be shown that the electric field at a distance r from the inner conducter is given by: E = \frac{V}{r ln\frac{b}{a}} Any help would be much...
  12. N

    Waves in a coaxial cable: Boundary conditions

    Homework Statement Hi all. I have the following expression, which relates the incoming amplitude with the reflected amplitude at a point x = L in a coaxial cable: A_{\text{reflected}} = \frac{R-Z_0}{R+Z_0}A_{\text{incoming}}. Here R is the resistance at the point x = L and Z0 is the...
  13. H

    Comparing sound waves to waves in a Coaxial Cable aka T.E.M.

    Homework Statement Compare sound waves to waves in coaxial cables a.k.a. T.E.M. I really have no idea how to answer this question. I've been researching and researching, and so far i can't find any information about WAVES for coaxial cables. Any help? Thanks. Homework Equations...
  14. J

    What is the equation for capacitance of a coaxial cable?

    Homework Statement http://smg.photobucket.com/albums/v68/jumpboyb/?action=view&current=scan0001.jpg" Pretty much looking for a general equation for capacitance of a coaxial cable per meter length. given: -a diagram (click link) -two radii -dielectric material -outer conductor is...
  15. T

    Auxiallry Field in a Coaxial Cable

    Homework Statement A coaxial cable consists of two very long cylindrical tubes, separated by linear insulating material of magnetic susceptibility χm (see Figure). A current I flows down the inner conductor and returns along the outer one, in each case the current distributes itself...
  16. S

    Coaxial cable and magnetic field

    Homework Statement a coaxial cable carries current as follows: (see attachment) at point P, 0.3 meters from the central axis, the magnetic field is 0.005 Teslas, what is current, I? Homework Equations magnetic field solenoid, B = mu_0(n)I where mu_) is constant = 4pi*10^-7, n is...
  17. J

    What Is the Optimal Inner Radius to Minimize Electric Field in a Coaxial Cable?

    Homework Statement If anyone could clarify this statement for me, I'm having a bit of difficulty interpreting what the heck I'm supposed to do: "For a given potential difference V0 between the inner and outer conductors and for a given fixed value of b, determine the inner radius a for which...
  18. E

    Calculating RC-Constant of Coaxial Cable

    Hi, I am doing an experiment with a coaxial cable and i want to Count out it expected RC-constant for the cable. I have measured the resistance for the cable, but when i count the RC, the resistansen that will be used only is the half of it resistans measured in the beginning. Why...
  19. E

    Electric Potential within coaxial cylinder

    Homework Statement A long metal cylinder with radius a is supported on an insulating stand on the axis of a long, hollow metal tube with radius b. Thew positive charge per unit length on the inner cylinder is \lambda, and there is an equal negative charge per unit length on the outer cylinder...
  20. E

    Magnetic flux between coaxial conductors

    Homework Statement A coaxial conductor has the length L. The inner conductor of radius a carries a current I in the z direction. The outer conductor is very thin and has the radius b. Calculate the total magnetic flux enclosed within the conductors. Homework Equations Magnetic flux...
  21. H

    Coaxial Cylindrical Conductors

    Homework Statement Two coaxial cylindrical conductors are shown. The inner cylinder has radius a = 2 cm, length 10 m, and carries a total charge of Q inner = +8nC. The outer cylinder has an inner radius b = 6 cm, outer radius c= 7 cm, length 10 m, and carries a total charge of Q outer =...
  22. C

    Coaxial Cylindrical Conductors

    Homework Statement What would the equipotential or e-field lines look like when staring down the axis of the two finite cylinders? Will the E-field lines be radial or are they different because the cylinders aren't infinite?
  23. T

    Off-set Coaxial Cable - Capacitance

    Hi, As you know the capacitance per unit length of a standard coaxial cable is C_{coax} = \frac{2 \pi \varepsilon_{0} \varepsilon_{r}}{\ln{\frac{b}{a}}} where b is the radius of the cable and a is radius of the central conductor. . If we only want to know the capacitance of a...
  24. B

    What is the Physics behind the Coaxial Cable?

    Homework Statement "A coaxial cable consists of an inner wire and a concentric cylindrical outer conductor. If the conductors carry equal but opposite charges, show that there is no net charge on the outside of the outer conductor. Homework Equations Gauss's Law The Attempt at a...
  25. C

    Electric Field in Coaxial Cable

    Homework Statement GIVEN: a=radius of inner electrode = 0.05 cm b=radius of outer electrode = 0.5 cm Vo = 130 V QUESTION: What is the electric field at surface of the inner electrode in units of V/m? Homework Equations Given equations Potential at radius r b/w inner&outer electrodes...
  26. J

    Inductance of a Coaxial cable

    hiya guys, I'm having a large amount of trouble with a problem that I've been working through (currently revising for an uncoming exam in electromagnetism, along with a lot of other things). the problem is stated as follows (condensed): coaxial cable - inner cylinder radius a, out cylinder...
  27. S

    V to get C. Calculating Max Capacitance of Coaxial Capacitor

    Homework Statement Consider a coaxial capacitor. If the inner radius is 5mm, the length is 3 cm, and the voltage rating of the capacitor is 2kV, what is the maximum capacitance if the dielectric between the two conductors is 2.3, and E breakdown is 15MV/m. Homework Equations E_r =...
  28. A

    Coaxial Cable Impedance: Why Length Doesn't Affect It | Explained with Model

    Why is the coaxial cable impedance independent of it's length? I am considering the model shown in the attached picture. Since the resistance, capacitance and inductance are all dependent of the length of the cable in one way or another how come the impedance is not? I also can't find any...
  29. K

    Vector potential in a coaxial cable

    Homework Statement I have to find the magnetic vector potential in a round coaxial cable. The internal conductor has a finite (known) conductivity. The external conductor is a perfect electrical conductor. Both the radius of the internal and the external conductors are known. I have to assume...
  30. N

    Coaxial pair of infinitely long charged solid conductors

    A) By definition linear charge density is Q/L. So for the inner conductor with 2λ I want to say it is 2Q/infinity but this cannot be right. I am sure using Guass's law produces a correct answer but I cannot see anyway to relate it to λ or length of the conductors for that matter B) For...
  31. Reshma

    Resistance between coaxial cylinders

    Two coaxial cylinders, inner radius a and outer radius b are separated by a material of conductivity given by \sigma (r) = k/r for some constant 'k'. Find the resistance between the cylinders. Here the conductivity is a function of position and the charge density is not zero in the resistive...
  32. Reshma

    Coaxial Solenoids: Finding Magnetic Field

    This one is from Griffiths. Two coaxial long solenoids each carry current I, but in opposite directions. The inner solenoid has radius 'a' and has 'n1' turns per unit length. The outer solenoid has radius 'b' and has 'n2' turns per unit length. Find the magnetic field \vec B in three...
  33. N

    Metal ring repelled from AC coaxial coil

    I thought people helped on this forum? If anything is unclear just ask, I'm checking for posts every minute. Come on people I have to get this done by 5 pm. I've gotten a little further. I believe it has something to do with mutual inductance. A metal ring (no current) is brought close to a...
  34. C

    Internal Forces in Coaxial Bars of Different Materials

    i have attached a doc file. it shows two coaxial circular bars of different material and a force(30kn) is applied in the top. I think the internal forces in both the bars will be 30kn. Am i correct. bar1 is made of steel and bar 2 of aluminium. the total length of the structure is 10metres.
  35. A

    Magnetic field of a coaxial cable

    The figure below is a cross-sectional view of a coaxial cable. The center conductor is surrounded by a rubber layer, which is surrounded by an outer conductor, which is surrounded by another rubber layer. In a particular application, the current in the inner conductor is 1.86 A out of the page...
  36. E

    Coaxial cable - Signal on oscillosope?

    Hello all, I once wanted to plug two coaxial cables together (tv - antenna), and when I touched the coaxial cable coming from the antenna, I got an electric shock (a weak one, like if you get an electric shock if you are charged and touch metal). My questions: 1) Why did I get an...
  37. Clausius2

    Fuel injector surrounded by a coaxial air stream

    Maybe you, chemical people could answer my question. Imagine a fuel injector surrounded by a coaxial air stream. The fuel and air flow are parallel, coaxial and axisymmetric. Both fluids obey ideal gas equation. Let's consider steady and compressible flow, i.e, variations of \rho are...
  38. N

    Checking Speed of EM Waves in Coaxial Lines with Pulse Function

    why we should use the pulse function in function generator when we need to check the speed of electromagnetic wave in coaxial line ?? why we can't use the other like sawtooth function??
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