What Is the Phase Velocity vp of Light of Wavelength λ?

Click For Summary
SUMMARY

The phase velocity (vp) of light with wavelength (λ) is defined by the equation vp = w/k, where w represents angular frequency and k represents the wave number. The relationship between group velocity (vg) and phase velocity is expressed as vg = vp(1 + λ/n * (dn/dλ)). To determine vp given a refractive index function n(λ), one must rewrite w in terms of λ and n(λ) and apply the chain rule for differentiation. This discussion focuses on deriving vp from the provided equations and relationships.

PREREQUISITES
  • Understanding of wave mechanics and light propagation
  • Familiarity with the concepts of angular frequency (w) and wave number (k)
  • Knowledge of refractive index (n) as a function of wavelength (n(λ))
  • Basic calculus, specifically the chain rule for differentiation
NEXT STEPS
  • Explore the derivation of phase velocity in different media using specific n(λ) functions
  • Learn about the implications of group velocity and phase velocity in optical fibers
  • Investigate the relationship between refractive index and wavelength in various materials
  • Study advanced calculus techniques for differentiating complex functions
USEFUL FOR

Students and professionals in physics, optical engineering, and anyone studying wave phenomena in various media will benefit from this discussion.

coltin.walsh
Messages
7
Reaction score
0

Homework Statement



see:

http://www.flickr.com/photos/55153239@N03/6371848305/

Homework Equations



vp = w/k

vg = dw/dk

The Attempt at a Solution



I know the relationship of:

vg = vp(1+lambda/n * (dn/dlambda))

but i don't know where to go from here..
 
Last edited by a moderator:
Physics news on Phys.org
1. given n(λ), what is phase velocity vp of light of wavelength λ?
2. as you state, w/k = vp. So how about rewriting w in terms of λ and n(λ), using (1) above?
3. use chain rule dw/dk = dw/dλ*dλ/dk
 

Similar threads

Replies
1
Views
7K
  • · Replies 1 ·
Replies
1
Views
3K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 2 ·
Replies
2
Views
3K
Replies
6
Views
7K
  • · Replies 18 ·
Replies
18
Views
6K
  • · Replies 7 ·
Replies
7
Views
4K
  • · Replies 4 ·
Replies
4
Views
2K