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Resistance Formula:
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The resistance of a material can be calculated from its resistivity using the fundamental formula that relates these electrical properties. Resistivity is an intrinsic property of a material, while resistance depends on both the material and its physical dimensions.
The calculator uses the resistance formula:
Where:
Explanation: The resistance is directly proportional to the length of the conductor and inversely proportional to its cross-sectional area, with resistivity as the proportionality constant.
Details: Calculating resistance from resistivity is essential for designing electrical circuits, selecting appropriate wire sizes, predicting power losses, and understanding material behavior in electrical applications.
Tips: Enter resistivity in Ω·m, length in meters, and cross-sectional area in square meters. All values must be positive numbers. Common materials have specific resistivity values (e.g., copper: 1.68×10⁻⁸ Ω·m).
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 shape or size.
Q2: Why does resistance increase with length?
A: Longer conductors provide more obstacles for electrons to travel through, increasing the overall resistance to current flow.
Q3: Why does resistance decrease with larger cross-sectional area?
A: Larger cross-sectional areas provide more pathways for electrons to flow, reducing the resistance similar to how wider pipes allow more water flow.
Q4: 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.
Q5: How does temperature affect resistivity?
A: For most metals, resistivity increases with temperature due to increased atomic vibrations that impede electron flow.