A Bubble is a biphasic object in every sense of the word. First, as a
concept. Indeed, its production is within everyone’s reach as long as
they have soap, a frame and their breath at their disposal. Yet, the
physics behind their very existence and the phenomena associated with
them remain puzzling questions that involve complex notions. Second,
they are literally made up of two phases: a gaseous and a liquid. The
combination, nature and distribution of these phases are responsible
for the unique behaviour of bubbles. Among other things, bubbles are
easily deformed by external fields, which make them a wonderful object
to highlight their effects.
In this work, we investigate the different effects that external fields
and the body forces related to them have on the bubbles shapes. More
precisely, we describe the deformation that bubbles undergo under an
electric or a magnetic field. These reshaping are linked both to the
applied fields properties and to those of the liquids used to make the
bubbles. In addition, the substrate also appears to have an influence on
the deformation. We show that these dependencies can be expressed by
dimensionless numbers that describe the competition between the forces
involved. Moreover, we find that the functions relating the shapes and
these dimensionless numbers are linear under weak fields. We obtain
these linear functions and, using them, we properly define what weak
fields are. With these results, we are able to propose a general guide
on how to handle, control and deform bubbles. Furthermore, by com-
paring the deformation of bubbles and droplets under similar fields, we
demonstrate that bubbles are a wonderful object to illustrate the very
nature of the forces acting on them.