The intensity of electric field required to balance a proton of mass 1.7×10−27kg and charge 1.6×10−19C is nearly
1×10−7 V/m
1×10−5 V/m
1×107 V/m
1×105 V/m
Since qE=mg or E=mgq=1.7×10−27×9.81.6×10−19
=10.0×10−8=1×10−7 V/m