1. What is Electrical Resistivity?

Electrical resistivity is a fundamental property of materials that quantifies how strongly they oppose electric current. For copper, the resistivity is \( 1.68 \times 10^{-8} \, \Omega \cdot m \) at 20°C, making it an excellent conductor.

2. How Does the Calculator Work?

The calculator uses the resistivity formula:

Where:

• \( R \) — Resistance in ohms (Ω)
• \( \rho \) — Resistivity of copper = \( 1.68 \times 10^{-8} \, \Omega \cdot m \)
• \( L \) — Length of wire in meters (m)
• \( A \) — Cross-sectional area in square meters (m²)

Explanation: The resistance increases with length and decreases with cross-sectional area. For circular wires, \( A = \pi r^2 = \pi (d/2)^2 \).

3. Importance of Resistivity Calculation

Details: Calculating wire resistance is crucial for electrical design, power transmission efficiency, voltage drop calculations, and selecting appropriate wire gauges for different applications.

4. Using the Calculator

Tips: Enter the wire length and diameter in meters. Ensure values are positive and realistic for accurate calculations. For American Wire Gauge (AWG) conversions, use standard reference tables.

5. Frequently Asked Questions (FAQ)

Q1: Why is copper used for electrical wiring?
A: Copper has low resistivity, excellent conductivity, good mechanical strength, corrosion resistance, and is readily available, making it ideal for electrical applications.

Q2: How does temperature affect copper resistivity?
A: Copper resistivity increases with temperature. The temperature coefficient for copper is approximately 0.00393 per °C at 20°C.

Q3: What is the difference between resistance and resistivity?
A: Resistivity is an intrinsic material property, while resistance depends on both the material and the geometry (length and cross-section) of the conductor.

Q4: How do I convert wire diameter to cross-sectional area?
A: For circular wires, use \( A = \pi r^2 = \pi (d/2)^2 \), where d is the diameter and r is the radius.

Q5: What are typical copper wire applications?
A: Electrical wiring in buildings, power transmission lines, motors, transformers, electronic circuits, and various electrical components.