Explain the formation of London forces.

(N/A) Atoms and nonpolar molecules are electrically symmetrical and have no dipole moment because their electronic charge cloud is symmetrically distributed.
However,a dipole may develop momentarily even in such atoms and molecules.
Suppose we have two atoms $A$ and $B$ in the close vicinity of each other.
In the initial state,there is a symmetrical distribution of the electronic charge cloud (see figure $a$).
It may so happen that momentarily,the electronic charge distribution in one of the atoms,say $A$,becomes unsymmetrical,i.e.,the charge cloud is more on one side than the other. This creates an instantaneous dipole in atom $A$.
This instantaneous dipole in atom $A$ distorts the electronic charge cloud of the neighboring atom $B$,thereby inducing a dipole in it. This is called an induced dipole.
The temporary attractive force between the instantaneous dipole and the induced dipole is known as the London dispersion force (see figures $b$ and $c$).