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Resistivity Formula:
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Resistivity (ρ) is a fundamental property of materials that quantifies how strongly they oppose electric current. It is an intrinsic property that depends on the material's composition and temperature, independent of its shape or size.
Resistivity is calculated using the formula:
Where:
Explanation: This formula relates the material's intrinsic property (resistivity) to its measurable electrical resistance and physical dimensions.
Details: Resistivity calculation is crucial for material selection in electrical engineering, designing conductors and insulators, quality control in manufacturing, and understanding material properties for various applications.
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 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 size or shape.
Q2: What are typical resistivity values for common materials?
A: Copper: ~1.68×10⁻⁸ Ω·m, Aluminum: ~2.82×10⁻⁸ Ω·m, Glass: ~10¹² Ω·m, Rubber: ~10¹³ Ω·m.
Q3: How does temperature affect resistivity?
A: For most metals, resistivity increases with temperature. For semiconductors, resistivity decreases with temperature.
Q4: What are the units of 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 science?
A: Resistivity helps classify materials as conductors, semiconductors, or insulators, and is essential for designing electrical components and circuits.