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Today's Topics:
1. What is a Wave? (John Denker)
2. Re: What is a Wave? (John Denker)
3. Re: What is a Wave? (Bernard Cleyet)
4. Re: What is a Wave? (John Denker)
5. Re: What is a Wave? (Dan L. MacIsaac)
Message: 1
Date: Sat, 07 Feb 2015 14:30:09 -0700
From: John Denker <jsd@av8n.com>
To: phys-l@phys-l.org
Subject: [Phys-L] What is a Wave?
Message-ID: <54D683E1.7010507@av8n.com>
Content-Type: text/plain; charset=utf-8
Hi --
I collected some resources and some thoughts on the topic
of "What Is a Wave?"
1 Examples and Counterexamples
1.1 Waves
1.2 Non-Waves
2 What is a Wave?
3 What is a Wave Equation?
4 Reflection from an Impedance Mismatch
5 Nonlinearity and Dispersion
6 References
It's a first draft, very incomplete, but still you may
find some bits of it to be useful.
In particular: If anybody has a better definition of
"what is a wave", please let us know! I've seen lots
of definitions, but the simple ones are not good, and
the good ones are not simple.
Also: I would sure like to see a demonstration of a
wave hitting an impedance mismatch /without/ a speed
mismatch. This should not be particularly hard to do
using a Shive-style torsion wave machine. It might
make a nice science-fair project.
------------------------------
Message: 2
Date: Sat, 07 Feb 2015 15:25:24 -0700
From: John Denker <jsd@av8n.com>
To: Phys-L@Phys-L.org
Subject: Re: [Phys-L] What is a Wave?
Message-ID: <54D690D4.8080303@av8n.com>
Content-Type: text/plain; charset=windows-1252
I collected some resources and some thoughts on the topic
of "What Is a Wave?"
1 Examples and Counterexamples
1.1 Waves
1.2 Non-Waves
2 What is a Wave?
3 What is a Wave Equation?
4 Reflection from an Impedance Mismatch
5 Nonlinearity and Dispersion
6 References
It's a first draft, very incomplete, but still you may
find some bits of it to be useful.
In particular: If anybody has a better definition of
"what is a wave", please let us know! I've seen lots
of definitions, but the simple ones are not good, and
the good ones are not simple.
Also: I would sure like to see a demonstration of a
wave hitting an impedance mismatch /without/ a speed
mismatch. This should not be particularly hard to do
using a Shive-style torsion wave machine. It might
make a nice science-fair project.
------------------------------
Message: 3
Date: Sat, 7 Feb 2015 17:17:02 -0800
From: Bernard Cleyet <bernard@cleyet.org>
To: Phys-L@Phys-L.org
Subject: Re: [Phys-L] What is a Wave?
Message-ID: <AEED07E7-4FE7-4FA1-94CA-CA66E6DB387A@cleyet.org>
Content-Type: text/plain; charset=utf-8
On 2015, Feb 07, , at 14:25, John Denker <jsd@av8n.com> wrote:
Also: I would sure like to see a demonstration of a
wave hitting an impedance mismatch /without/ a speed
mismatch. This should not be particularly hard to do
using a Shive-style torsion wave machine. It might
make a nice science-fair project.
I often like to show my ignorance.
This seems an oxymoron.
cables w/ differing impedance. The transmitted wave will have a different speed, no?
No R:
5.1) Velocity of Propagation
The velocity of a signal in free space is the speed of light or 2.997925 x 108 m/s (this is generally accepted to be approximately 3 x 108 m/s). A theoretical loss less coaxial cable working at high frequencies has a velocity of propagation that can be calculated from Formula 5.1.
Formula 5.1
Where vp is the velocity of propagation in m/s
C is the distributed capacitance per unit length in pF
L is the distributed inductance per unit length in ?H
Derived electrical parameters[edit]
? Characteristic impedance in ohms (?). Neglecting resistance per unit length for most coaxial cables, the characteristic impedance is determined from the capacitance per unit length () and the inductance per unit length (). The simplified expression is (). Those parameters are determined from the ratio of the inner (d) and outer (D) diameters and the dielectric constant (). The characteristic impedance is given by[7]
bc maths declined and uses argumentum ad verecundiam (i.e. search engine)
------------------------------
Message: 4
Date: Sat, 07 Feb 2015 19:07:15 -0700
From: John Denker <jsd@av8n.com>
To: Phys-L@Phys-L.org
Subject: Re: [Phys-L] What is a Wave?
Message-ID: <54D6C4D3.2020300@av8n.com>
Content-Type: text/plain; charset=utf-8
On 02/07/2015 06:17 PM, Bernard Cleyet wrote:
cables w/ differing impedance.
Easy for me to build.
Hard for intro-level student to get a feel for what's going on.
With a rope or a torsion wave machine you can literally /feel/
the wave ... as well as see it.
These are kids who aren't real sure how to interpret an XY
graph, let alone an oscilloscope trace, much less a time
domain reflectometer trace.
------------------------------
Message: 5
Date: Sat, 7 Feb 2015 21:39:13 -0500
From: "Dan L. MacIsaac" <danmacisaac@gmail.com>
To: Phys-L@Phys-L.org
Subject: Re: [Phys-L] What is a Wave?
Message-ID: <082D29A5-EC25-4869-8984-5F38639667C7@gmail.com>
Content-Type: text/plain; charset=us-ascii
End of Phys-l Digest, Vol 122, Issue 5
**************************************
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