Energy travels at group velocity and not phase velocity?

AI Thread Summary
Energy travels at group velocity rather than phase velocity, as group velocity represents the speed at which the envelope of a wave packet moves, correlating with energy transfer. However, it is important to note that group velocity does not always equate to the speed of energy transfer in all scenarios. A general proof supporting this concept can be found in a referenced paper discussing the equivalence of group velocity and energy transport. The discussion emphasizes the need to understand the conditions under which group velocity accurately reflects energy movement. Overall, the relationship between group velocity and energy transfer is complex and context-dependent.
zebanaqvi
Messages
4
Reaction score
0
How to prove that energy travels at group velocity and not phase velocity?
 
Physics news on Phys.org
Start here: http://en.wikipedia.org/wiki/Group_velocity

Note that the group velocity is not always the speed for energy transfer!

A general proof is given in this paper: http://journals.aps.org/archive/abstract/10.1103/PhysRev.105.1129
"General Theorems on the Equivalence of Group Velocity and Energy Transport"
 
Last edited by a moderator:

Thread 'Is calling fictitious forces "not real" just about terminology?'

Hi there, im studying nanoscience at the university in Basel. Today I looked at the topic of intertial and non-inertial reference frames and the existence of fictitious forces. I understand that you call forces real in physics if they appear in interplay. Meaning that a force is real when there is the "actio" partner to the "reactio" partner. If this condition is not satisfied the force is not real. I also understand that if you specifically look at non-inertial reference frames you can...
View full post »

Thread 'Derivation of Hamilton's Principle: Questions'

I have recently been really interested in the derivation of Hamiltons Principle. On my research I found that with the term ##m \cdot \frac{d}{dt} (\frac{dr}{dt} \cdot \delta r) = 0## (1) one may derivate ##\delta \int (T - V) dt = 0## (2). The derivation itself I understood quiet good, but what I don't understand is where the equation (1) came from, because in my research it was just given and not derived from anywhere. Does anybody know where (1) comes from or why from it the...
View full post »

Similar threads

Difference between Group and phase velocity
Replies
2
Views
2K
I Phase and group velocity for the wave function
Replies
14
Views
781
I Calculating phase shift between two sinusoidal waves
Replies
8
Views
2K
Understanding the Concept of Phase Velocity: Explained Simply
Replies
4
Views
2K
Can group velocity be greater than phase velocity?
Replies
2
Views
6K
Phase velocity and wave velocity
Replies
15
Views
7K
Single frequency- phase and group velocity?
Replies
1
Views
2K
Group velocity dispersion and normal, anomalous dispersion?
Replies
2
Views
5K
I What Determines the Speed and Clarity of Signals in Wave Physics?
Replies
6
Views
2K
B Why in two block systems do both blocks tend to have the same velocity?
Replies
6
Views
1K

Hot Threads

Recent Insights

Back
Top