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Resistance Formula:
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The resistance formula (R = ρ × L / A) calculates the electrical resistance of a material based on its resistivity (ρ), length (L), and cross-sectional area (A). This fundamental equation in electrical engineering helps determine how much a material opposes the flow of electric current.
The calculator uses the resistance formula:
Where:
Explanation: The formula shows that resistance is directly proportional to both the resistivity and length of the material, and inversely proportional to its cross-sectional area.
Details: Accurate resistance calculation is crucial for designing electrical circuits, selecting appropriate wire gauges, preventing energy loss, and ensuring electrical safety in various applications.
Tips: Enter resistivity in Ω·m, length in meters, and cross-sectional area in m². All values must be positive numbers greater than zero.
Q1: What is resistivity?
A: Resistivity is an intrinsic property of a material that quantifies how strongly it opposes the flow of electric current. Different materials have different resistivity values.
Q2: How does length affect resistance?
A: Resistance increases with length - longer conductors have higher resistance because electrons must travel a greater distance.
Q3: How does cross-sectional area affect resistance?
A: Resistance decreases with increasing cross-sectional area - thicker conductors have lower resistance because there's more space for electrons to flow.
Q4: What are typical resistivity values?
A: Copper has about 1.68×10⁻⁸ Ω·m, while silver has about 1.59×10⁻⁸ Ω·m. Insulators like rubber can have resistivity values as high as 10¹³-10¹⁶ Ω·m.
Q5: Can this formula be used for AC circuits?
A: This formula calculates DC resistance. For AC circuits, impedance must be considered, which includes both resistance and reactance components.