Describe briefly dipole-induced dipole forces.

Attractive forces are also operative between a molecule having a dipole moment and a molecule without any dipole moment like CH₄. As the size of the atom increases, the influence of the electric dipole on it also increases. The electron cloud of the molecule is distorted in the electric field of the permanent dipole. This causes a shift in the centre of gravity of the negative charge relative to the nuclear charge and leads to the formation of an induced dipole moment. The interaction energy is proportional to 1/r⁶and also depends on upon the dipole moment of the permanent dipole and the polarizability of the second molecule. The interaction between two dipolar molecules also includes additive dipole-dipole interactions.