Vastupanuväärtus

Vastupanuväärtus refers to the electrical resistance of a material per unit length and per unit cross-sectional area. It is a fundamental property of a material that quantifies how much it opposes the flow of electric current. The symbol commonly used for vastupanuväärtus is the Greek letter rho (ρ).

The formula for calculating the resistance (R) of a conductor is given by R = ρ(L/A), where L is the length of the conductor and A is its cross-sectional area. This formula highlights that resistance is directly proportional to vastupanuväärtus and length, and inversely proportional to the cross-sectional area. Materials with low vastupanuväärtus, such as copper and silver, are considered good conductors and are used in electrical wiring. Conversely, materials with high vastupanuväärtus, like rubber and glass, are insulators and are used to prevent the flow of electricity.

Vastupanuväärtus is an intrinsic property, meaning it depends solely on the material itself and is independent of the object's shape or size. It is typically measured in ohm-meters (Ω·m). Temperature also significantly affects vastupanuväärtus; for most conductors, resistance increases with increasing temperature. This temperature dependence is also a key characteristic of different materials and is utilized in applications like thermistors. Understanding vastupanuväärtus is crucial in designing and analyzing electrical circuits and systems.