BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a view showing a construction of a surface voltmeter;
FIG. 2 is a flowchart showing an operation flow of the surface voltmeter;
FIG. 3 is a graph showing relationships between current specifying voltage and electrode voltage;
FIG. 4A is a schematic view of the surface voltmeter;
FIG. 4B is a view showing a schematic view of a surface voltmeter in accordance with a comparative example;
FIG. 5A is a circuit diagram schematically showing connections between a capacitance and a stray capacitance and an ampere meter;
FIG. 5B is a circuit diagram schematically showing connections between a capacitance and a stray capacitance and an ampere meter in accordance with the comparative example;
FIG. 6 is a graph showing another example of an operation for obtaining a reference voltage;
FIG. 7 is a view showing a construction of another surface voltmeter; and
FIG. 8 is a graph showing relationships between current specifying voltage and electrode voltage.