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Resistivity Formula:
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Resistivity (ρ) is a fundamental property of materials that quantifies how strongly they oppose the flow of electric current. It's an intrinsic property that depends on the material's composition and temperature, but not on its shape or size.
The calculator uses the resistivity formula:
Where:
Explanation: The formula shows that resistivity is directly proportional to resistance and cross-sectional area, and inversely proportional to length.
Details: Resistivity calculation is crucial for material selection in electrical engineering, designing conductors and insulators, quality control in manufacturing, and understanding material properties in research and development.
Tips: Enter resistance in ohms, cross-sectional area in square meters, and length in meters. All values must be positive numbers greater than zero.
Q1: What's the difference between resistance and resistivity?
A: Resistance depends on the material's shape and size, while resistivity is an intrinsic property of the material itself, independent of its dimensions.
Q2: What are typical resistivity values for common materials?
A: Copper: ~1.68×10⁻⁸ ohm m, Aluminum: ~2.82×10⁻⁸ ohm m, Glass: ~10¹² ohm m, Rubber: ~10¹³-10¹⁶ ohm m.
Q3: How does temperature affect resistivity?
A: For most metals, resistivity increases with temperature. For semiconductors, resistivity decreases with temperature.
Q4: What units are used for resistivity?
A: The SI unit is ohm meter (Ω·m), but ohm centimeter (Ω·cm) is also commonly used (1 Ω·m = 100 Ω·cm).
Q5: Why is resistivity important in material selection?
A: Different applications require different resistivity values - conductors need low resistivity, insulators need high resistivity, and semiconductors need intermediate values.