What is the SI unit for resistivity?
The SI unit for resistivity is the ohm-metre (Ω⋅m).
Electrical resistivity, often denoted by the Greek letter ρ (rho), is a fundamental property of a material that quantifies how strongly it resists electrical current. A low resistivity indicates a material that readily allows electric current to flow, making it a good conductor, while high resistivity signifies a poor conductor, or a good insulator.
The SI Unit: Ohm-Metre (Ω⋅m)
As per the International System of Units (SI), the standard unit for electrical resistivity is the ohm-metre. This unit is represented by the symbol Ω⋅m, combining the ohm (Ω) for electrical resistance and the metre (m) for length.
Practical Example of Ohm-Metre
To better grasp the meaning of ohm-metre, consider this practical scenario:
- Imagine a solid cube of a material measuring 1 cubic metre (1 m³).
- If you apply sheet contacts to two opposite faces of this cube, and the electrical resistance measured between these contacts is 1 ohm (1 Ω), then:
- The resistivity of that material is precisely 1 ohm-metre (1 Ω⋅m).
This example from Electrical resistivity and conductivity - Wikipedia illustrates how the unit connects resistance with the material's geometry (length and cross-sectional area).
Key Information at a Glance
For quick reference, here's a summary of the SI unit for resistivity:
Quantity | SI Unit | Symbol |
---|---|---|
Electrical Resistivity | Ohm-metre | Ω⋅m |
Knowing the resistivity of a material is crucial in various applications, from designing electrical circuits and components to understanding the behavior of semiconductors and insulators.