# Term: Electrical resistivity and conductivity

– Definition:

– Electrical resistivity is a property measuring a material’s resistance to electric current.

– It is represented by the Greek letter ρ and measured in ohm-metres.

– Electrical conductivity is the reciprocal of resistivity.

– Conductivity is represented by the Greek letter σ and measured in siemens per metre.

– Resistivity and conductivity are intrinsic properties of materials.

– Ideal case:

– Resistance is directly proportional to length and inversely proportional to cross-sectional area.

– Resistivity is expressed in ohm-metres.

– Resistivity is intrinsic and unaffected by geometric properties.

– Resistance varies with length and cross-sectional area.

– Conductivity is the inverse of resistivity.

– General scalar quantities:

– Resistivity varies with position in the material.

– Resistivity is the ratio of electric field to current density.

– Conductivity is the reciprocal of resistivity.

– Rubber has high resistivity and low conductivity.

– Copper has low resistivity and high conductivity.

– Material properties:

– Resistivity is an intrinsic property of materials.

– Pure copper wires have the same resistivity regardless of shape.

– Different materials have different resistivities.

– Resistivity determines the ease of current flow in a material.

– Conductivity is influenced by resistivity.

– Mathematical expressions:

– Resistivity is defined as the ratio of electric field to current density.

– Conductivity is the reciprocal of resistivity.

– Rubber has high resistivity and low conductivity.

– Copper has low resistivity and high conductivity.

– Ideal case simplifies resistivity and conductivity calculations.

**Electrical resistivity** (also called **volume resistivity** or **specific electrical resistance**) is a fundamental specific property of a material that measures its electrical resistance or how strongly it resists electric current. A low resistivity indicates a material that readily allows electric current. Resistivity is commonly represented by the Greek letter ρ (rho). The SI unit of electrical resistivity is the ohm-metre (Ω⋅m). For example, if a 1 m^{3} solid cube of material has sheet contacts on two opposite faces, and the resistance between these contacts is 1 Ω, then the resistivity of the material is 1 Ω⋅m.

Resistivity | |
---|---|

Common symbols | ρ |

SI unit | ohm metre (Ω⋅m) |

Other units | s (Gaussian/ESU) |

In SI base units | kg⋅m^{3}⋅s^{−3}⋅A^{−2} |

Derivations from other quantities | |

Dimension |

Conductivity | |
---|---|

Common symbols | σ, κ, γ |

SI unit | siemens per metre (S/m) |

Other units | (Gaussian/ESU) |

Derivations from other quantities | |

Dimension |

**Electrical conductivity** (or **specific conductance**) is the reciprocal of electrical resistivity. It represents a material's ability to conduct electric current. It is commonly signified by the Greek letter σ (sigma), but κ (kappa) (especially in electrical engineering) and γ (gamma) are sometimes used. The SI unit of electrical conductivity is siemens per metre (S/m). Resistivity and conductivity are intensive properties of materials, giving the opposition of a standard cube of material to current. Electrical resistance and conductance are corresponding extensive properties that give the opposition of a specific object to electric current.