Which metals have the lowest resistivity?
Electrical or thermal condutivity, resistivity, density and melting point
|TIBTECH||Electrical conductivity (10.E6 Siemens/m)||Electrical resistivity (10.E-8 Ohm.m)|
The electrical resistivity of a material is also known as its specific electrical resistance. It is a measure of how strongly a material opposes the flow of electric current. A definition of resistivity is the electrical resistance per unit length and per unit of cross-sectional area.
- More resistance means less current is flowing through the circuit. Equivalent resistance is a different way of indicating 'total' resistance, which we calculate differently for series and parallel circuits. In a series circuit, the different components are connected in a single, continuous loop.
- The resistivity of a material is the resistance of a wire of that material of unit length and unit cross-sectional area. The unit for resistivity is the ohm-metre. The resistivity of a material depends on its nature and the temperature of the conductor, but not on its shape and size.
- Resistivity and Temperature Coefficient at 20 C
Material Resistivity ρ (ohm m) Silver 1.59 x10-8 Copper 1.68 x10-8 Copper, annealed 1.72 x10-8 Aluminum 2.65 x10-8
Aluminum is lighter than copper. Aluminum has a resistivity varying from 2.65 to 2.82 × 10−8 Ω · m. Combined with it's light weight and alloyed with some other metals to make it stronger, aluminum is ideal for electrical cables.
- "Resistivities at 20 °C. Silver - 1.59 × 10−8 Ωm" 1.59 × 10−8 Ωm. Resistivity is a characteristic of a material that determines the ability of the material to oppose a flow of electrons, or electricity.
- An ohmmeter is an electrical instrument that measures electrical resistance, the opposition to an electric current. Megohmmeters (also a trademarked device Megger) measure large values of resistance. The unit of measurement for resistance is ohms (Ω).
- The resistance of an object (i.e., a resistor ) depends on its shape and the material of which it is composed. Resistivity ρ is an intrinsic property of a material and directly proportional to the total resistance R, an extrinsic quantity that depends on the length and cross-sectional area of a resistor.
As the graph shows, the resistivity of a substance is very much dependent on temperature. For most conductors, resistivity increases with rising temperature. At 20 °C, the resistivity of gold is approximately 2.44 × 10−8 ohm-m and steadily rises with increasing temperature.
- Aluminum is lighter than copper. Aluminum has a resistivity varying from 2.65 to 2.82 × 10−8 Ω · m. Combined with it's light weight and alloyed with some other metals to make it stronger, aluminum is ideal for electrical cables.
- The unit of resistivity is then ohm-meters (Ωm). Nichrome, a non-magnetic alloy that is commonly made up of 80% nickel and 20% chromium, has a resistivity ranging from 1.10 × 10−6 Ωm to 1.50 × 10−6 Ωm (0.00000110 Ωm to 0.00000150 Ωm) and a very high boiling point (~1400 °C).
- We have also learnt that the resistivity (symbol: ρ) of the conductor (or material) relates to the physical property from which it is made and varies from material to material. For example, the resistivity of copper is generally given as: 1.72 x 10-8 Ω.m.
Updated: 16th October 2019