How To Calculate Resistance Of A Copper Wire

Resistance Formula:

\[ R = \rho \frac{L}{A} \]

Resistance (R):

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1. What Is Electrical Resistance?

Electrical resistance is a measure of the opposition to the flow of electric current in a material. For copper wires, resistance depends on the wire's dimensions and the material's inherent resistivity.

2. How Does The Resistance Calculator Work?

The calculator uses the resistance formula:

\[ R = \rho \frac{L}{A} \]

Where:

\( R \) — Electrical resistance (Ω)
\( \rho \) — Resistivity of the material (Ω·m)
\( L \) — Length of the wire (m)
\( A \) — Cross-sectional area of the wire (m²)

Explanation: The resistance increases with length and decreases with cross-sectional area. Copper has a low resistivity of 1.68×10⁻⁸ Ω·m, making it an excellent conductor.

3. Importance Of Resistance Calculation

Details: Accurate resistance calculation is crucial for electrical system design, voltage drop analysis, power loss estimation, and selecting appropriate wire gauges for specific applications.

4. Using The Calculator

Tips: Enter length in meters, cross-sectional area in square meters, and resistivity in ohm-meters. For copper wire, the default resistivity is 1.68×10⁻⁸ Ω·m. All values must be positive.

5. Frequently Asked Questions (FAQ)

Q1: Why is copper commonly used for electrical wiring?
A: Copper has low resistivity (1.68×10⁻⁸ Ω·m), excellent conductivity, good mechanical strength, and resistance to corrosion, making it ideal for electrical applications.

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

Q3: What is the relationship between wire gauge and resistance?
A: Smaller gauge numbers indicate thicker wires with lower resistance. American Wire Gauge (AWG) is commonly used to specify wire sizes.

Q4: How do I calculate cross-sectional area for round wires?
A: For round wires, area = π × (diameter/2)². Diameter can be found from wire gauge tables or direct measurement.

Q5: What are typical resistance values for household wiring?
A: For standard 14 AWG copper wire (1.63 mm diameter), resistance is about 8.45 Ω per 1000 meters. Actual values depend on specific wire gauge and length.