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Electrical Resistivity Formula:
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Electrical resistivity (ρ) is a fundamental property of materials that quantifies how strongly they oppose the flow of electric current. It's measured in ohm-meters (Ω·m) and is the reciprocal of electrical conductivity.
The calculator uses the resistivity formula:
Where:
Explanation: The equation shows that resistivity is proportional to the resistance and cross-sectional area, and inversely proportional to the length of the material.
Details: Resistivity is crucial for selecting materials in electrical engineering, designing circuits, and understanding material properties. It helps determine appropriate materials for wires, resistors, and other electrical components.
Tips: Enter resistance in ohms, cross-sectional area in square meters, and length in meters. All values must be positive numbers.
Q1: What's 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 size or shape.
Q2: What are typical resistivity values?
A: Conductors like copper have low resistivity (~1.7×10⁻⁸ Ω·m), insulators like glass have high resistivity (~10¹⁰-10¹⁴ Ω·m), and semiconductors are in between.
Q3: How does temperature affect resistivity?
A: For most metals, resistivity increases with temperature. For semiconductors, it typically decreases with temperature.
Q4: What's the relationship between resistivity and conductivity?
A: Conductivity (σ) is the reciprocal of resistivity: σ = 1/ρ. Materials with high resistivity have low conductivity.
Q5: Why is resistivity important in wire selection?
A: Lower resistivity materials are preferred for wires to minimize energy loss as heat, but cost and mechanical properties must also be considered.