1. What Is Electrical Resistance?

Electrical resistance is a measure of the opposition to the flow of electric current in a material. It is a fundamental property in physics and electrical engineering that determines how much current will flow for a given voltage.

2. How Does The Resistance Formula Work?

The resistance formula is based on Ohm's law and material properties:

Where:

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

Explanation: Resistance increases with length (more material to travel through) and decreases with cross-sectional area (more pathways for electrons).

3. Importance Of Resistance Calculation

Details: Calculating resistance is crucial for designing electrical circuits, selecting appropriate wire sizes, preventing overheating, and ensuring proper functioning of electrical devices and systems.

4. Using The Calculator

Tips: Enter resistivity in Ω·m, length in meters, and cross-sectional area in square meters. All values must be positive numbers greater than zero.

5. Frequently Asked Questions (FAQ)

Q1: What is resistivity and how is it different from resistance?
A: Resistivity is an intrinsic property of the material itself, while resistance depends on both the material and its physical dimensions (length and cross-sectional area).

Q2: What are typical resistivity values for common materials?
A: Copper: 1.68×10⁻⁸ Ω·m, Aluminum: 2.82×10⁻⁸ Ω·m, Silver: 1.59×10⁻⁸ Ω·m, Iron: 1.0×10⁻⁷ Ω·m.

Q3: How does temperature affect resistance?
A: For most conductors, resistance increases with temperature due to increased atomic vibrations that impede electron flow.

Q4: What is the unit of resistance?
A: The SI unit of resistance is the ohm (Ω), named after Georg Simon Ohm.

Q5: Can resistance be negative?
A: In ordinary conductors, resistance is always positive. Negative resistance can occur in some semiconductor devices under specific conditions.