The phase-velocity tag has no wiki summary.
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4answers
678 views
In superluminal phase velocities, what is it that is traveling faster than light?
I understand that information cannot be transmitted at a velocity greater than speed of light. I think of this in terms of the radio broadcast: the station sends out carrier frequencies $\omega_c$ but ...
6
votes
3answers
274 views
Controllable faster-than-light phase velocity
This is not another question about faster-than-light travel or superluminal communication. I totally appreciate the speed limit capped by physical laws (or theories.)
Just curious, since there is no ...
4
votes
7answers
410 views
Information relationship to Special Relativity
How do we write mathematically that "information" cannot go faster than light? And along a similar line of thought, how do we relate "information" with special relativity. Lastly, what is the ...
3
votes
1answer
171 views
Fermat principle: which index of refraction?
I am somewhat puzzled by a common formulation of the Fermat principle (light travel time), because it contains index of refraction related to phase velocity while light travel time through a slab of ...
3
votes
1answer
554 views
Phase and Group Velocity of Electromagnetic Waves
Moving charges produce oscillating electric and magnetic fields -we have an electromagnetic wave.
In terms of moving charges or at the level of charges, what is phase velocity and group velocity of ...
3
votes
2answers
593 views
Group Velocity and Phase Velocity of Matter Wave?
In quantum mechanics, what is the difference between group velocity and phase velocity of matter wave? How can it also be that phase velocity of matter wave always exceeds the speed of light?
2
votes
1answer
354 views
Rotating mirror - Foucault's measurement of light speed
Some time ago I came across a secondary web source on measurement of light speed in water made by Foucault around 1850. I append its redrawn scheme below (light is reflected from the rotating mirror ...
1
vote
3answers
2k views
How do you find the velocity function of a mechanical wave?
With the form $y(x,t)=A\sin(kx-\omega t+\phi_0)$, there are two variables, How do I find the velocity? I don't know I can apply derivative with two variables.
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vote
2answers
536 views
What does the velocity of a wave mean?
I know that the velocity of a wave is given by $v=\lambda f$ but what does this velocity represent in the physical sense. For instance, if I am told a car moves at a velocity of 5 $m/s$ I know that ...
1
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1answer
442 views
Deriving group velocity
At the introduction to quantum mechanic phase $v_p$ and group $v_g$ velocities are often presented. I know how to derive $v_p$ and get equation:
$$
\scriptsize
v_p=\frac{\omega}{k}
$$
What i dont ...
1
vote
1answer
184 views
Why doesn't anomalous dispersion allow faster-than-light propagation?
It seems that the phase velocity of light could be greater than $c$, if $\sqrt{\epsilon \mu} < 1/c$, i.e. for anomalous dispersion.
Are there examples of such media? For diamagnetics it seems ...
0
votes
1answer
86 views
Wavefronts and phase velocity faster than $c$
Lets assume we have parallel wavefronts in a glass of water:
and we put an inclined rod on the water surface:
related to a very small inclining, Vy velocity is greater or much greater then Vx ...
0
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0answers
36 views
What is the relation between phase velocity and generator frequency in a rectangular waveguide?
Could you help me to find relations between phase velocity and generator frequency in a rectangular waveguide?
