Talk:Node (physics)

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"There are two types of wave propagation: longitudinal and transverse. An example of the former is the guitar string, which creates sound waves."

This strikes me as incorrect; I thought the vibration of a guitar string is a transverse wave (the resultant sound waves are longitudinal, though). Powers ^T 19:12, 21 November 2006 (UTC)[reply]

You're right. The way the wave is propogated is by a transverse vibration. The wave itself is longitudinal. I'll fix it. 72.1.206.174 16:49, 2 May 2007 (UTC)[reply]

This article needs some major cleanup. It doesn't explain the idea of nodes/antinodes well, nor how they are formed. It does not talk about how the nodes relate to the natural frequency of an object, nor interference patterns. There should also be information pertaining to the superposition principle, and the resonant lengths. I could go on and on. Work on this article please!! 72.1.206.174 16:53, 2 May 2007 (UTC)[reply]

"In transmission lines a voltage node is a current antinode, and a voltage antinode is a current node."

Wouldn't this depend upon the complex impedance of the line? —Preceding unsigned comment added by Bgamari (talk • contribs) 06:31, 30 November 2009 (UTC)[reply]

The article currently asserts that antinodes occur "midway" between nodes, which I interpret to be exactly halfway between them. But this assertion seems intuitively true only for symmetric waves. In fact, I think that I can construct a counterexample to this claim. 99.76.14.134 (talk) 07:51, 3 January 2014 (UTC)[reply]

As long as the transmission medium of a one-dimensional standing wave is homogeneous, so the speed of the wave is constant along the medium, two oppositely moving sinusoidal waves of the same frequency will create a standing wave which itself has a sinusoidal amplitude as a function of distance along the medium. ${\displaystyle y_{\text{max}}=A\sin(kx)}$ The nodes occur where the sine wave amplitude goes to zero, at points

${\displaystyle x=\;0,\;\pi /k,\;2\pi /k,\;3\pi /k,\cdots }$

The antinodes occur at points where the sine wave's amplitude is maximum, which occur at points equidistant between the nodes

${\displaystyle x=\pi /2k,\;3\pi /2k,\;5\pi /2k,\;7\pi /2k,\cdots }$

This describes the common examples used in the article, as standing waves on a guitar string, or electromagnetic waves on s terminated transmission line. If the medium is nonhomogeneous, such as a guitar string with a varying thickness, or a transmission line with a verying characteristic impedance the standing waves will not be sinusoidal and the antinodes will not be midway between the nodes. --Chetvorno^TALK 19:13, 25 September 2014 (UTC)[reply]