How can there be an induced dipole in a substance with a permanent dipole moment? I thought an induced dipole can occur only in a non-polar substance. Yet, this is part of the proposed dipole-induced dipole mechanism for dynamic light scattering experiments.
An electric field will change the electron distribution in a molecule whether that molecule is polar or not. If the molecule starts with no dipole then an external field will create a dipole. If the molecule already has a dipole (like water) then the external field will increase or decrease the dipole or change its direction.
You could argue that induced dipole is a little misleading for a molecule that already had a dipole, but you could read it as induced additional dipole.