[Encyclios]

Electrical properties of solids include:

• conductivity;
• resistance;
• impedance;
• capacitance;
• piezoelectricity (electro-mechanical).

Electrical conductors such as metals and alloys are contrasted with electrical insulators such as glasses and ceramics. Semiconductors behave somewhere in between. Whereas electrons cause conductivity in metals, both electrons and holes contribute to the current in semiconductors. Alternatively, ions support electric current in ionic conductors.