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Resistivity Formula:
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Electrical resistivity (ρ) is a fundamental property that quantifies how strongly a material opposes the flow of electric current. It's an intrinsic property that depends on the material's composition and temperature, not its shape or size.
The calculator uses the resistivity formula:
Where:
Explanation: This formula relates the intrinsic resistivity of a material to its measured resistance and geometric dimensions. The resistance increases with length and decreases with cross-sectional area.
Details: Resistivity calculations are 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 (Ω), cross-sectional area in square meters (m²), and length in meters (m). All values must be positive numbers. Ensure consistent units for accurate results.
Q1: What's the difference between resistance and resistivity?
A: Resistance depends on both material and geometry, while resistivity is an intrinsic property of the material itself, independent of shape and size.
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: ~10¹⁰-10¹⁴ Ω·m, Rubber: ~10¹³-10¹⁶ Ω·m.
Q3: How does temperature affect resistivity?
A: For most conductors, resistivity increases with temperature. For semiconductors, resistivity decreases with temperature. Superconductors have zero resistivity below critical temperature.
Q4: What units should I use for cross-sectional area?
A: Use square meters (m²) for consistency with SI units. For wires, you can use diameter in meters and calculate area as π×(d/2)².
Q5: Can this formula be used for all materials?
A: This formula works for homogeneous, isotropic materials with uniform cross-section. For anisotropic materials or complex geometries, more advanced calculations are needed.