Re: [Phys-L] What is a Wave?

[Bernard Cleyet <bernard@cleyet.org>]

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 µH

http://chemandy.com/technical-articles/sitting-waves/standing-waves-article6.htm  


===========

Derived electrical parameters[edit]
	• Characteristic impedance in ohms (Ω). 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]
   

http://en.wikipedia.org/wiki/Coaxial_cable#Physical_parameters  


bc  maths declined and uses argumentum ad verecundiam  (i.e. search engine)