Resistance Calculator
Calculate resistance from voltage, current, power, or combine resistors
Resistance Calculator
Calculate electrical resistance using Ohm's Law (V/I), power formulas, or combine resistors in series and parallel. Supports unit conversions between ohms, kilohms, and megohms.
📏 Resistance Calculator
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Formula Used
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📚 Understanding Electrical Resistance
What is Resistance?
Electrical resistance measures how strongly a material opposes the flow of electric current. It is measured in ohms (Ω), named after Georg Simon Ohm. Higher resistance means less current flows for the same voltage.
Series vs Parallel
In series, resistances add up directly. In parallel, the total resistance is always less than the smallest individual resistor. Two equal resistors in parallel give half the resistance of one.
Factors Affecting Resistance
Resistance depends on material (resistivity), length (longer = more resistance), cross-sectional area (thicker = less resistance), and temperature (most metals increase resistance when heated).
Resistance Formulas
Ohm's Law
From voltage and power
From power and current
Combining Resistors
Series: total resistance increases
Parallel: total resistance decreases
Common Material Resistivities
| Material | Resistivity (Ω·m × 10⁻⁸) | Type |
|---|---|---|
| Silver | 1.59 | Best conductor |
| Copper | 1.68 | Standard wiring |
| Gold | 2.44 | Connectors |
| Aluminum | 2.65 | Power lines |
| Iron | 9.71 | Structural |
| Nichrome | 110 | Heating elements |