Instability of a drop in relation to its own or polarizing charges

Regularities in the changes of the potential energy of an oscillating spherical and virtually spheroidal drop on the threshold of stability loss in relation to its self-charge are studied. For an unloaded drop in a uniform electrostatic field, in which it takes the equilibrium form of a spheroid extended across the field and for which there is no simple conclusion for the criterion of instability in relation to a polarizing charge, a simple and physically transparent method of assessment of the criterion in order of magnitude based on comparison of the potential energy of capillary and electrostatic forces is offered mathematically.