What is a Resistor?
A resistor is a passive electronic component that limits or controls the flow of current in a circuit. Think of it as a speed bump on a road — it slows things down.
Why Do We Need Resistors?
- Protect LEDs from burning out
- Set voltage levels in circuits
- Create voltage dividers
- Limit current to safe levels
The Color Code System
Resistors use colored bands to indicate their value. Here's the standard 4-band code:
| Color | Digit | Multiplier |
|---|---|---|
| Black | 0 | ×1 |
| Brown | 1 | ×10 |
| Red | 2 | ×100 |
| Orange | 3 | ×1K |
| Yellow | 4 | ×10K |
| Green | 5 | ×100K |
| Blue | 6 | ×1M |
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Types of Resistors
Fixed Resistors
Most common type — the resistance value never changes.
Variable Resistors (Potentiometers)
Allow you to adjust resistance — like a volume knob.
Thermistors
Resistance changes with temperature — used in thermometers.
Quick Calculation
To protect an LED (2V forward voltage) with a 5V supply:
R = (Vsupply - VLED) / ILED
R = (5 - 2) / 0.02 = 150Ω
Always round up to the nearest standard value!
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