_, Suppose we have a gas in a closed fixed container, each molecule of which has a permanent dipole moment Lt; Permanent means that the orientation of the dipole moment can change, but its magnitude cannot. The gas is E affected by a homogeneous electric field (ie the strength of the field does not depend on the location), which polarizes the gas by interacting with the dipole moments of the gas molecules. It is assumed that the mutual interactions between gas molecules, including dipoledipole interactions, are vanishingly small The interaction energy of one molecule with an electric field is 8 : u ' E_ We now consider the case of the weak interaction uwg