London Dispersion forces are seen in all the atoms and the molecules; however, it is the exclusive force binding nonpolar molecules. Nonpolar molecules are made of two or more atoms, and the electronegativity between two atoms in a covalent bond is less than 0.5. Therefore, no charges are separated to create poles in nonpolar molecules or atoms. Despite not having poles, nonpolar molecules interact using a weak force of attraction known as the London Forces. Nonpolar molecules are H2, N2, He, CH4 and CO2, etc.
The electrons in the nonpolar molecules are in continuous random motion. This constant fluctuation in the electron position results in a situation wherein most electrons will concentrate towards one end of the molecule, creating a negative pole, and the other end will turn into a positive pole. The formation of temporary dipoles in a few molecules has enough power to distort the electron clouds of any nearby molecules. That is an instantaneous dipole in a few molecules induced or forced dipole formation in others. Such molecules then try and align their poles, and their interaction becomes stronger. This type of interaction is called the London force or Induced Dipole interactions.
The above excerpt supports the chapter Intermolecular Forces part of CurlyArrows' Introductory Organic Chemistry Course. Preview the Book.
Related reading: Introduction to Vander Wall forces, London Dispersion Force
