Wave packets has a group velocity of [tex]v_{group}=\frac{d\omega}{dk}[/tex] and its phase velocity is [tex]v_{phase}=\frac{\omega}{k}[/tex] Show that the group velocity and the phase velocity are related by: [tex]v_{group} = v_{phase} - \lambda\frac{dv_{phase}}{d\lambda}[/tex] Can someone please tell me where to start on this problem?
All u need to know besides the rules of differentiation is [tex] k=:\frac{2\pi}{\lambda} [/tex] Daniel. PS.Compute the RHS of your equality and show it matches the LHS.