Resistance opposes current flow, measured in ohms (Ω). It is fundamental to circuit design, described by Ohm's law: V = I × R.
Ohm's Law
V = IR. If you know any two of voltage, current, resistance, you can find the third. Power: P = I²R = V²/R.
Resistance Units
- 1 MΩ = 1,000 kΩ
- 1 kΩ = 1,000 Ω
Common values: 100 Ω, 1 kΩ, 10 kΩ, 100 kΩ, 1 MΩ.
Color Codes
Black=0, Brown=1, Red=2, Orange=3, Yellow=4, Green=5, Blue=6, Violet=7, Gray=8, White=9. 4-band: digit-digit-multiplier-tolerance. Brown-black-red-gold = 1 kΩ ±5%.
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Frequently Asked Questions
How do I read resistor color codes?
First two bands = digits, third = multiplier, fourth = tolerance. Red-red-brown-gold = 220 Ω ±5%.