All the following are examples of electric force except?
A.) an electron pushing on another electron
B.) An proton pulling on an electron
C.) A neutron pushing on another neutron
D.) An electron pulling on a proton

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.