It turns out that determining the speed of sound in metals is kind of a mess.
There is formula, sqrt (Young's Modulus / density), that gives an approximation of the answer. http://hyperphysics.phy-astr.gsu.edu/hbase/sound/souspe2.html For nickel, I find 200GPa and 8.94e3 kg*m^-3; the formula then gives 4740 m/s. But this is only 84% of a purported value I found in http://www.olympus-ims.com/en/ndt-tutorials/thickness-gage/appendices-velocities, which gives 5630 m/s. It seems even harder to find good answers for copper, I think because it's hard to find a single value of Young's Modulus. Wikipedia gives a range of 110GPa - 128GPa; http://www.engineeringtoolbox.com/young-modulus-d_417.html is the citation for the wikipedia page and gives 117 (grin). With density = 8.96e3 kg*m^-3, 110GPa and 128GPa give 3500 and 3780 m/s which are 75% and 81%, respectively, of the value 4660 m/s found in that same link. But this other link http://www.engineeringtoolbox.com/sound-speed-solids-d_713.html gives a completely different value for speed of sound in copper, about 3900 m/s, which agrees more closely with the estimate from the formula. For 70/30 cupronickel alloy, http://www.copper.org/applications/cuni/txt_properties.html shows a value of 22 * 10^6 psi±5% ≈ 152GPa for Young's Modulus and 8.95 for the density. This gives 4120 m/s by formula. The above examples all suggest this value is low, but there's no way to know how low. The second link above includes this text: *The table below lists typical longitudinal wave ultrasonic velocities in a variety of common materials that can be measured with ultrasonic thickness gages. Note that this is only a general guide. The actual velocity in these materials may vary significantly due to a variety of causes such as specific composition or microstructure, grain or fiber orientation, porosity, and temperature. This is especially true in the case of cast metals, fiberglass, plastics, and composites. For best accuracy in thickness gaging, the sound velocity in a given test material should always be measured by performing a velocity calibration on a sample of known thickness.* The goal here is construct an electrode that will define a standing wave at a certain frequency *f* that is near 430KHz but is not known precisely. Given all of the above this is going to be tricky. We cannot just vary *f* to fit the electrode size because it's not arbitrary. We cannot know the size of the electrode to construct for a given *f* unless we have very accurate knowledge of the speed of sound in the electrode material. In addition we must accurately control the other conditions, e.g. temperature, because they will affect the speed of sound in the material. And all this fussing is just to find out whether the phenomenon is real or not. If this stuff was easy everybody would be doing it. Jeff On Thu, Nov 22, 2012 at 1:54 PM, Jeff Berkowitz <pdx...@gmail.com> wrote: > However a U.S. nickel is 75/25 copper/nickel. It might be possible to > figure out the speed of sound using information in this thread: > > http://www.physicsforums.com/showthread.php?t=277330 > > I'll look at it later. > > Jeff > > > On Thu, Nov 22, 2012 at 1:38 PM, Jeff Berkowitz <pdx...@gmail.com> wrote: > >> Interesting. A U.S. nickel is 1.95mm thick. >> >> >> On Thu, Nov 22, 2012 at 1:21 PM, James Bowery <jabow...@gmail.com> wrote: >> >>> It's hard to know where to begin here but let me just say this that >>> given the speed of sound in >>> nickel<http://www.olympus-ims.com/en/ndt-tutorials/thickness-gage/appendices-velocities/> >>> : >>> >>> 5630m/s >>> >>> and 430kHz: >>> >>> 5630m/s;430kHz?mm >>> >>> ([5630 * meter] / second) * (430 * [kilo*hertz])^-1 ? milli*meter >>> = 2.0838194 mm >>> >>> In other words, a 2mm electrode should exhibit resonance at ~430kHz. >>> >>> >>> On Thu, Nov 22, 2012 at 2:47 PM, Jones Beene <jone...@pacbell.net>wrote: >>> >>>> On the contrary James, at least two of us did look closely at this >>>> possibility [electrode acoustics]. **** >>>> >>>> ** ** >>>> >>>> My associate went to trouble to find and download a mpeg sound file of >>>> a bicycle bell of the same general size as Davey’s, and plugged it into a >>>> program for this kind of analysis – in fact it is dedicated bell analysis >>>> software that has proved very accurate for electrodes in the past. The >>>> natural acoustic of this hemisphere are nowhere close.**** >>>> >>>> ** ** >>>> >>>> The main freq is 4,445.5 Hz, with some sub harmonics, the lowest being >>>> around 521/545 Hz, but those are so faint as to be discarded. Higher >>>> harmonics are barely above noise.**** >>>> >>>> ** ** >>>> >>>> Thus, since the acoustics of the electrodes were off by two orders of >>>> magnitude over the signature sound, we did not think that electrode >>>> acoustics were in any way relevant as an alternative explanation, or >>>> otherwise worth pursuing.**** >>>> >>>> ** ** >>>> >>>> Jones**** >>>> >>>> ** ** >>>> >>>> ** ** >>>> >>>> *From:* James Bowery **** >>>> >>>> ** ** >>>> >>>> As I previously >>>> advised<http://www.mail-archive.com/vortex-l@eskimo.com/msg73144.html> >>>> :**** >>>> >>>> ** ** >>>> >>>> "Look at the acoustics of the electrodes."**** >>>> >>>> ** ** >>>> >>>> Since this advice seemed to make no impact on the discourse here at >>>> vortex-l, let me expand:**** >>>> >>>> ** ** >>>> >>>> Acoustic resonance in the metallic electrodes does have a reasonable >>>> chance of bearing directly on the creation of the "nuclear active >>>> environment" hypothesized to exist. I don't think I need to expland on >>>> list the possibilities here.**** >>>> >>>> ** ** >>>> >>>> Moreover, if one looks at the speed of sound in metals, the "430kHz >>>> LENR signature" regime corresponds to the thickness of the cathodes >>>> frequently reported as exhibiting the phenomena.**** >>>> >>>> ** ** >>>> >>>> Need I say more?** >>>> >>>> ** ** >>>> >>> >>> >> >
