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Resistance Formula:
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The resistivity and resistance formula (R = ρL/A) calculates the electrical resistance of a material based on its intrinsic resistivity, length, and cross-sectional area. This fundamental equation in electrical engineering and physics helps determine how much a material opposes the flow of electric current.
The calculator uses the resistance formula:
Where:
Explanation: The formula shows that resistance is directly proportional to the material's resistivity and length, and inversely proportional to its cross-sectional area.
Details: Accurate resistance calculation is crucial for designing electrical circuits, selecting appropriate wire sizes, calculating power losses, and ensuring electrical safety in various applications from household wiring to industrial systems.
Tips: Enter resistivity in Ω·m, length in meters, and cross-sectional area in square meters. All values must be positive numbers greater than zero for accurate calculation.
Q1: What is the difference between resistance and resistivity?
A: Resistance is a property of a specific object, while resistivity is an intrinsic property of the material itself, independent of the object's dimensions.
Q2: What are typical resistivity values for common materials?
A: Copper: 1.68×10⁻⁸ Ω·m, Aluminum: 2.82×10⁻⁸ Ω·m, Silver: 1.59×10⁻⁸ Ω·m, Iron: 1.0×10⁻⁷ Ω·m.
Q3: How does temperature affect resistance?
A: For most conductors, resistance increases with temperature due to increased atomic vibrations that impede electron flow.
Q4: What is the unit of resistivity?
A: The SI unit of resistivity is ohm-meter (Ω·m), though ohm-centimeter (Ω·cm) is also commonly used.
Q5: Can this formula be used for all materials?
A: This formula applies to uniform conductors with constant cross-section. For semiconductors and complex geometries, additional factors must be considered.