(i) What is the phase velocity of EM radiation in free space?
(ii) What is its group velocity?
Are the solutions below correct?
Using the definition as per this page:
(i) Vp = (C^2) / Vg
(ii) Vg = (C^2) / Vp
Phase velocity of EM radiation in free space Watch
- Thread Starter
- 16-05-2013 18:27
- Community Assistant
- 22-05-2013 11:59
So starting from Vp=w/k and Vg=dw/dk
w=kVp so Vg=Vp+kdVp/dk
since k=2pi/wavelength (let wavelength=l I'm LaTex illiterate)
for E/M radiation in a refractive index 'n' Vp=c/n
so Vg=(c/n)(1+(l/n)(dn/dl)) in a vacuum n=1=constant across all w/l as non-dispersive I think
so Vp=Vg=c and everyone is happy