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Specific Resistance Formula:
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Specific resistance (also known as resistivity) is an intrinsic property of materials that quantifies how strongly they oppose electric current. The formula ρ = R × A / L relates resistance to the material's dimensions and its inherent resistivity.
The calculator uses the specific resistance formula:
Where:
Explanation: This formula shows that resistivity is directly proportional to resistance and cross-sectional area, and inversely proportional to length.
Details: Calculating specific resistance is crucial for material selection in electrical engineering, designing conductors and insulators, understanding material properties, and predicting electrical behavior in circuits.
Tips: Enter resistance in ohms (Ω), cross-sectional area in square meters (m²), and length in meters (m). All values must be positive numbers greater than zero.
Q1: What is the difference between resistance and resistivity?
A: Resistance depends on the material's dimensions, while resistivity is an intrinsic property of the material itself, independent of 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, Silver: ~1.59×10⁻⁸ Ω·m, Glass: ~10¹⁰-10¹⁴ Ω·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: Low resistivity materials are chosen for conductors, while high resistivity materials are used for insulators and heating elements.