resistività

Resistivity is a fundamental electrical property of a material that quantifies how strongly that material opposes the flow of electric current. It is an intrinsic property, meaning it does not depend on the object's shape or size, only on the material itself and the ambient conditions like temperature. Resistivity is typically represented by the Greek letter rho (ρ).

The relationship between resistivity, the dimensions of a conductor, and its electrical resistance is given by the formula R = ρL/A, where R is the resistance, L is the length of the conductor, and A is its cross-sectional area. From this, we can see that a material with higher resistivity will have a higher resistance for a given length and cross-sectional area, thus impeding current more effectively.

The unit of resistivity in the International System of Units (SI) is the ohm-meter (Ω⋅m). Materials with very low resistivity, such as copper and silver, are excellent electrical conductors and are used in wiring. Conversely, materials with very high resistivity, like rubber and glass, are insulators and are used to prevent the flow of electricity. Temperature significantly affects resistivity; for most conductors, resistivity increases with increasing temperature, while for semiconductors and insulators, it generally decreases.