Electricity that is stationary like the electric charge on an object.
Electrostatic motors driven by static electricity were manufactured
experimentally earlier than electromagnetic motors. However, they were the same size as
conventional motors and could hardly match electromagnetic motors in performance. The energy
density of the electrostatic motor is much lower than that of electromagnetic motors because of the
limitations of their dielectric strength. This is the reason why their practical application has
been difficult. The miniaturization of electrostatic motors changes the sitter, and the breakdown
voltage of solid insulation materials increases as they become thinner. With a thin insulation film,
a breakdown voltage of 2 MV/cm can be easily obtained, and the electrostatic attraction force is
quite strong at around 0.65 MPa. With insulation by gas, if the voltage is below the lower limit at
which discharge starts as explained by Paschen's law, no discharge will occur even though the gap is
small. Because this lower limit is 330 V in air, if, for example, 300 V is applied to a gap of 1
μm, an attraction force of around 0.4 MPa can be obtained.