What is Resistivity? – Unit, Formula | New Topic [2024]

In this note, we are going to discuss about a topic called “What is Resistivity?“, unit of resistivity and formula of resistivity as well. welcome to Poly Notes Hub, a leading destination for Engineering Notes.

Author Name: Arun Paul.

What is Resistivity?

Resistivity is a fundamental attribute of materials that characterizes their ability to resist the passage of electrical current. It is represented by the symbol ρ (rho) and measured in ohm-meters (Ω⋅m).

Resistivity is determined by a variety of parameters, including the material’s composition, temperature, and physical structure. Materials with high resistivity obstruct the flow of electric current more efficiently than those with low resistivity. Conductors, such as metals, have low resistivity, which allows electric current to flow freely through them. Insulators, on the other hand, have a high resistance, which limits the flow of current.

The resistivity of a substance can be determined using the following formula:

ρ = R * A / L

Where;

• ρ is the resistivity of the material,
• R is the resistance of the material in ohms (Ω),
• A is the cross-sectional area of the material in square meters (m²),
• L is the length of the material in meters (m) through which the current flows.

On which factors resistivity depends

Resistivity of a material is depends on various factors like –

• Material: Different materials have varying resistivities. For example, metals have low resistivity, but insulators have high resistance.
• Temperature: Most materials’ resistivity tends to increase with temperature. This is because higher temperatures create more atomic vibrations, which interfere with the movement of charge carriers, limiting the passage of electricity.
• Structure: The configuration of atoms or molecules within a substance can influence its resistivity. For example, impurities or imperfections in conductors can enhance resistance by scattering charge carriers.
• Electrical Field: Field-dependent resistivity is a phenomena in which resistivity changes in response to an electric field. This phenomenon occurs in some semiconductors and can be used in electronic devices such as field-effect transistors.