Define resistivity. What are the factors affecting the resistivity of a conductor.

Resistivity is a fundamental property of materials that characterizes their ability to resist the flow of electric current. It is denoted by the symbol “ρ” (rho) and is measured in ohm-meters (Ω·m) in the International System of Units (SI).
In science, The formula that relates resistivity (ρ), resistance (R), length (L), and cross-sectional area (A) of a conductor is:
R=ρ L/A
Here, R is the resistance of the conductor, ρ is the resistivity, L is the length of the conductor, and A is the cross-sectional area.

Now, Factors affecting the resistivity of a conductor include:

1. Material: Different materials have different resistivities. For example, materials like copper and aluminum have low resistivities, making them good conductors, while materials like rubber or glass have higher resistivities, making them insulators.

2. Temperature: Resistivity generally increases with temperature. As the temperature of a conductor increases, the vibrating atoms and electrons within the material collide more frequently, impeding the flow of electrons and increasing resistance.

3. Impurities: The presence of impurities in a material can increase its resistivity. Impurities create lattice defects and disrupt the regular arrangement of atoms, hindering the flow of electrons.

4. Crystal Structure: The crystal structure of a material can influence its resistivity. Crystalline structures tend to have lower resistivities compared to amorphous or disordered structures.

5. Cross-Sectional Area: As per the formula, resistivity is inversely proportional to the cross-sectional area of the conductor. A larger cross-sectional area reduces the resistance and, consequently, the resistivity.

6. Length: Resistivity is directly proportional to the length of the conductor. Increasing the length of the conductor increases its resistance and, therefore, its resistivity.