Calculate the planetary phase angle (counterclockwise from earth, a = 1.0 au) that a probe may correctly complete a hohmann transfer orbit to venus (a = 0.7 au)

Students in an introductory physics lab are performing an experiment with a parallel-plate capacitor made of two circular aluminum plates, each 11 cm in diameter, separated by 1.0 cm. how much charge can be added to each of the plates before a spark jumps between the two plates? for such flat electrodes, assume that value of 3×106n/c of the field causes a spark.