Mohamed Saad E1-Din Abdel Gafoor Abdel Magid2018-10-022018-10-022006http://hdl.handle.net/123456789/13034The problem of the charged spheroidal bubble is studied using the virial method. The conditions that are necessary for equilibrium are deduced and the oscillation of the bubble is studied . The frequencies belonging to the second order harmonics are found . Further extension of the virial theorem is made by studying the viscous fluid sphere in an incompressible viscous fluid giving the different and necessary virial equations of motion for both the exterior and the interior media and then the equilibrium state is studied.enMathematicsThesis