The London van der Waals force is approximatly given by F=-c *a^-7 where a is the distance between two neutral atoms and c is something like this:(adsbygoogle = window.adsbygoogle || []).push({});

C=-23*hbar*c/4pi*(alpha1*alpha2)

where alpha1 and alpha2 =(epsilon-1)/(4pi*N)

and N is the atom number density and epsilon the permittivity.

--> Question 1: Does that mean if I have a body with 10^30 atoms the moledule number density is 10^30?

Now from the force between neutral atoms we can get to the Casimir-force. We can then just calclulate how much one atom of Plate A is attracted by the atoms of the other plates. Doing so with all atoms on Plate A we can sum over all the resulting forces and have the Casimir-Force.

Question 2: is this correct?

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# Homework Help: London van der Waals force

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