Q1Electrical Materials
Question
Q.1. Define resistivity and factors affecting resistivity.
Answer
Resistivity (ρ) is the intrinsic resistance of a material per unit dimensions (R = ρL/A, unit Ω·m); it is affected by temperature, impurities/alloying, mechanical strain, and crystal structure defects.
Resistivity (specific resistance, ρ) is the property of a material quantifying its opposition to current flow independent of specimen geometry, defined through R = ρL/A where R is resistance, L length, and A cross-sectional area; its SI unit is ohm-meter (Ω·m). The main factors affecting resistivity are: temperature (resistivity of metals rises nearly linearly with temperature due to increased lattice vibrations scattering electrons); impurities and alloying (foreign atoms distort the lattice and increase scattering, raising resistivity); mechanical stress/strain and cold working (deformation introduces dislocations that scatter electrons); and crystal defects/grain boundaries (imperfections increase electron scattering and hence resistivity).