- #1

Jano L.

Gold Member

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## Main Question or Discussion Point

Imagine light of frequency [itex]\Omega[/itex] enters a liquid and propagates in the z direction. Its velocity is reduced to c/n. This leads to reduction of its wavelength to 1/n of the vacuum wavelength and the wave is described by the macroscopic electric field

[tex]

\mathbf E (\mathbf x,t) = \mathbf E_0 \cos(\Omega t - n\Omega/c z).

[/tex]

However, does the reduction of the wavelength and speed occur also at the microscopic level?

Take one molecule of the liquid; it is surrounded by empty space, and is under action of the microscopic electromagnetic field. How would you describe this microscopic field, as a slowed-down wave

[tex]

\mathbf e (\mathbf x,t) = \mathbf e_0 \cos(\Omega t - n\Omega/c z).

[/tex]

or as a vacuum wave

[tex]

\mathbf e (\mathbf x,t) = \mathbf e_0 \cos(\Omega t - \Omega/c z).

[/tex]

or neither?

[tex]

\mathbf E (\mathbf x,t) = \mathbf E_0 \cos(\Omega t - n\Omega/c z).

[/tex]

However, does the reduction of the wavelength and speed occur also at the microscopic level?

Take one molecule of the liquid; it is surrounded by empty space, and is under action of the microscopic electromagnetic field. How would you describe this microscopic field, as a slowed-down wave

[tex]

\mathbf e (\mathbf x,t) = \mathbf e_0 \cos(\Omega t - n\Omega/c z).

[/tex]

or as a vacuum wave

[tex]

\mathbf e (\mathbf x,t) = \mathbf e_0 \cos(\Omega t - \Omega/c z).

[/tex]

or neither?