- #1

Dassinia

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Hello

I have this tab

http://img18.imageshack.us/img18/3317/eyph.png

Anf I have to find the group and phase velocities for a wavelength λ=550nm

v(phase)= c/n

v(group)=dw/dk

v(phase)*v(group)=c²/n²

I don't know how I can determine n for the wavelength of 550nm using the tab ?

I was absent the day of this course

Can I use the relation v(phase)*v(group)=c²/n² ?

Thanks !

## Homework Statement

I have this tab

http://img18.imageshack.us/img18/3317/eyph.png

Anf I have to find the group and phase velocities for a wavelength λ=550nm

## Homework Equations

v(phase)= c/n

v(group)=dw/dk

v(phase)*v(group)=c²/n²

## The Attempt at a Solution

I don't know how I can determine n for the wavelength of 550nm using the tab ?

I was absent the day of this course

Can I use the relation v(phase)*v(group)=c²/n² ?

Thanks !

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