1. What is Electrical Resistance?

Electrical resistance is a measure of the opposition to the flow of electric current through a material. It is measured in ohms (Ω) and depends on the material's properties and physical dimensions.

2. How Does the Calculator Work?

The calculator uses the resistance formula:

Where:

• \( R \) — Electrical resistance (Ω)
• \( L \) — Length of the conductor (m)
• \( \sigma \) — Electrical conductivity (S/m)
• \( A \) — Cross-sectional area (m²)

Explanation: Resistance is directly proportional to the length of the conductor and inversely proportional to both conductivity and cross-sectional area.

3. Importance of Resistance Calculation

Details: Accurate resistance calculation is crucial for designing electrical circuits, selecting appropriate wire sizes, and ensuring proper functioning of electronic devices and power systems.

4. Using the Calculator

Tips: Enter length in meters, conductivity in siemens per meter (S/m), and area in square meters (m²). All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is the relationship between conductivity and resistivity?
A: Conductivity (σ) is the reciprocal of resistivity (ρ). The relationship is σ = 1/ρ, so the formula can also be written as R = ρL/A.

Q2: What are typical conductivity values for common materials?
A: Silver: ~6.3×10⁷ S/m, Copper: ~5.96×10⁷ S/m, Aluminum: ~3.5×10⁷ S/m, Iron: ~1.0×10⁷ S/m.

Q3: How does temperature affect resistance?
A: For most conductors, resistance increases with temperature. The relationship is given by R = R₀[1 + α(T - T₀)], where α is the temperature coefficient.

Q4: What is the difference between DC and AC resistance?
A: AC resistance (impedance) may be higher than DC resistance due to skin effect and proximity effect at higher frequencies.

Q5: When is this formula not applicable?
A: This formula assumes uniform material properties and cross-section. It may not be accurate for non-uniform materials, very high frequencies, or extreme temperatures.