An electric field can induce an electric dipole in a neutral atom or molecule by

Question

An electric field can induce an electric dipole in a neutral atom or molecule by pushing the positive and negative charges in opposite directions. The dipole moment of the induced dipole is directly proportional to the electric field at the atom or molecule. That is, p =E , where is called the polarizability of the molecule. A stronger electric field at the atom or molecule results in a more polarized molecule and causes a larger dipole moment p.

Now I already solved for all but one of the questions.

a.An ion with charge q is a distance r from a molecule with polarizability . Find an expression for the dipole moment induced in the molecule.

b.Find an expression for the force of the ion on the induced dipole Fionondipole. Assume that the distance r is much larger than the charge separation within the dipole.

The results i got were the same as other quesitons posted to this: http://www.chegg.com/homework-help/questions-and-answers/electric-field-induce-electric-dipole-neutral-atom-molecule-pushing-positive-negative-char-q8420017?trackid=3811ade6&strackid=641a7863&ii=1

what I need help with is this question part c:

c.The molecule has 16 times the mass of the ion. Find an expression for the force of the induced dipole on the ion F dipole on ion.

Explanation / Answer

dipole moment=p=alpha*E

here E=k*q/r^2

where k=coloumb's constant

hence p=alpha*k*q/r^2

electric field due to the dipole at a large distance d is given by k*p/d^3

so here field by the dipole at the location of charge q

=k*p/r^3

=k*alpha*k*q/r^5=k^2*alpha*q/r^5

force =electric field*charge

=k^2*alpha*q^2/r^5

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