Resistance Calculator Formula
Understand the math behind the resistance calculator. Each variable explained with a worked example.
Formulas Used
Resistance
resistance = voltage / currentVariables
| Variable | Description | Default |
|---|---|---|
voltage | Voltage(V) | 12 |
current | Current(A) | 0.5 |
How It Works
Resistance
Resistance measures how strongly a component opposes the flow of electric current.
Formula
R = V / I
Derived from Ohm's law. The unit is the ohm (Ω), named after Georg Ohm.
Worked Example
A 12 V battery drives 0.5 A through a resistor.
voltage = 12current = 0.5
- 01R = V / I
- 02R = 12 / 0.5
- 03R = 24 Ω
Frequently Asked Questions
What factors determine the resistance of a wire?
Resistance depends on the material (resistivity), length, cross-sectional area, and temperature: R = rho * L / A.
Does resistance change with temperature?
Yes. For most metals, resistance increases with temperature. For semiconductors, it typically decreases.
What is a resistor color code?
A system of colored bands on resistors that encode their resistance value. Each color represents a digit or multiplier.
Ready to run the numbers?
Open Resistance Calculator