This level of resistance indicates that the material is broadly an insulator, but has some conductivity. The term ‘surface resistivity’ means that the resistance is measured between two opposite edges of a square film. Because the resistance is independent of the length of the path, the unit is correct, although a figure of ‘ohms per square’ would be more common.
Generally, an increase of temperature increases conductivity, so that the surface resistivity would be expected to reduce as the temperature rises, and increase as it falls. However, an increase in moisture content will also increase conductivity, and a cold surface may absorb enough moisture for the resistivity to reduce quite markedly.
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