Question

What is phase velocity?

This one is confusing for me. I think I understood what group velocity means. It is like the speed of a wave packet moving along an axis?

Answer 1

If I remember MY tangle with phase velocity,

I THINK that it's the v=f lambda velocity for a wave with only one wavelength.

I THINK that group velocity is for a "collection" of waves presumably of different frequencies and the IDEA seems to be to find the speed at which the overall GROUP is moving.
The idea of "centre of gravity" popped into my head so I'll post it. Can't guarantee it's relevant here, though.
Yup these ideas confuse people (self) 'cos they're whistled through on the back of the usual pile of algebra.
I've read that the phase velocity is the rate of change of phase with time and that this is tantamount to v = f lambda.
But, if there's a number of waves in the group of different frequencies/wavelengths there may be no clearly defined phase change, and so no clear phase velocity.

http://perendis.webs.com

Answer 2

I remember (vaguely) that term "phase velocity" used when attending FAA's basic radar school at the Aeronautical Center, Oklahoma City, OK. It was used during the subject "Waveguide Theory." I too was confused about it as phase velocity could and did exceed the speed of light. This was in 1969 and I have not seen the term used again until now. Sorry that I can not add anything that would clarify your "confusion." I feel your pain.

Answer 3

@radar

so you saw the moon landing?!?!?! as in, for real?!?!

man/womankind's peak achievement, IMHO. by a million miles/ a country mile.

Answer 4

Yes, I've been here a long time, will be 78 years old next month.

Answer 5

@radar I salute you, sir. Your experience would be/is without estimable value, I think.
http://perendis.webs.com

Answer 6

Thanks osprey, experience was varied between military and FAA (both government). In this problem it didn't help solve the length of the tubes, I would think the dimensions would result in a frequency, and the beam for that thing may even consist of ions, electrons, or what have you lol.
I am impressed by your knowledge and the pursuit thereof, same goes for IrishBoy123. I was and am still impressed by the engineering that went into the SR-71 Blackbird which has been obsolete for several years now (satellite replacing it functions).

Answer 7

Well, Sir, something I actually learned, courtesy of a proxy knowledge of Professor Lise/lisa Meitner and Mileva Maric-Einstein, proxy and posthumously, was that it was some sort of (masochistic ?) honour/pleasure to begin to think about trying to follow what they were talking about. I pick the ladies, because of the problems they faced during their work, and I do not refer to the technical stuff.
I think that "we" owe it to people who actually have the "cutting edge" experience to say thank you, and to then pump them for all they're willing to give.
Sorry to ramble.