Resistor Color Code Chart
| Color | Digit | Multiplier | Tolerance |
|---|---|---|---|
| Black | 0 | ×1 | — |
| Brown | 1 | ×10 | ±1% (F) |
| Red | 2 | ×100 | ±2% (G) |
| Orange | 3 | ×1K | ±0.05% (W) |
| Yellow | 4 | ×10K | ±0.02% (P) |
| Green | 5 | ×100K | ±0.5% (D) |
| Blue | 6 | ×1M | ±0.25% (C) |
| Violet | 7 | ×10M | ±0.1% (B) |
| Grey | 8 | ×100M | ±0.01% (L) |
| White | 9 | ×1G | — |
| Gold | — | ×0.1 | ±5% (J) |
| Silver | — | ×0.01 | ±10% (K) |
Series vs Parallel Circuits
| Property | Series | Parallel |
|---|---|---|
| Total Resistance | R₁ + R₂ + R₃ | 1/(1/R₁ + 1/R₂ + 1/R₃) |
| Current | Same through all | Divides across branches |
| Voltage | Divides across resistors | Same across all |
| Total vs Individual | Always larger | Always smaller |
| If one fails (open) | Circuit breaks | Others still work |
Conductor Resistance Formula
R = L / (σ × A)
- R = resistance (ohms, Ω)
- L = conductor length (meters)
- σ = conductivity (siemens per meter, S/m)
- A = cross-sectional area (m²) = π(d/2)²
Conductivity of Common Materials
| Material | Conductivity (×10⁶ S/m) | Relative to Copper |
|---|---|---|
| Silver | 63.0 | 106% |
| Copper | 59.6 | 100% |
| Gold | 41.1 | 69% |
| Aluminum | 37.7 | 63% |
| Brass | 15.0 | 25% |
| Iron | 10.3 | 17% |
| Nichrome | 0.93 | 1.6% |
Common Resistor Values (E12 Series)
Standard resistor values follow a geometric sequence. The E12 series has 12 values per decade:
1.0, 1.2, 1.5, 1.8, 2.2, 2.7, 3.3, 3.9, 4.7, 5.6, 6.8, 8.2
Multiply by powers of 10: 10Ω, 12Ω, 15Ω ... 1kΩ, 1.2kΩ, 1.5kΩ ... 100kΩ, etc.