  When a colloidal gel dries through evaporation, cracks are usually formed,
which often reveal underlying processes at work during desiccation. Desiccating
colloid droplets of few hundred $\mu l$ size show interesting effects of
pattern formation and cracking which makes this an active subject of current
research. Since aqueous gels of clay are known to be strongly affected by an
electric field, one may expect crack patterns to exhibit a field effect. In the
present study we allow droplets of laponite gel to dry under a radial electric
field. This gives rise to highly reproducible patterns of cracks, which depend
on the strength, direction and time of exposure to the electric field. For a
continuously applied DC voltage, cracks always appear on dissipation of a
certain constant amount of energy. If the field is switched off before cracks
appear, the observed results are shown to obey a number of empirical scaling
relations, which enable us to predict the time of appearance and the number of
cracks under specified conditions.
