Learning Objective
Master potentiometer operation for analog input control, understand voltage dividers, and create smooth LED dimming with Arduino Uno.
What is a Potentiometer?
A potentiometer (often called a "pot") is a three-terminal variable resistor that allows you to manually adjust resistance by turning a knob or sliding a lever.
Construction
- Terminal 1: Connected to one end of resistive track (typically to 5V)
- Terminal 2 (Wiper): Center terminal - movable contact that slides along the track
- Terminal 3: Connected to other end of resistive track (typically to GND)
- Resistive Track: Carbon or cermet material with fixed total resistance (10kΩ in our case)
Key Specifications
- Total Resistance: 10kΩ
- Rotation Range: ~270°
- Taper Type: Linear (B-type)
- Power Rating: 0.1-0.5W typical
How a Potentiometer Works: Voltage Divider
A potentiometer acts as a voltage divider. When you connect the outer terminals to 5V and GND, the wiper outputs a voltage proportional to its position along the resistive track.
Voltage Divider Formula
Vout = Vin × (R2 / (R1 + R2))
Where:
- Vin = 5V (supply voltage)
- R1 = Resistance from 5V to wiper
- R2 = Resistance from wiper to GND
- R1 + R2 = 10kΩ (always constant)
Interactive visualization — available in the full lesson
| Knob Position | R1 (5V to Wiper) | R2 (Wiper to GND) | Output Voltage | Arduino analogRead() |
|---|---|---|---|---|
| Full Counter-Clockwise | 10kΩ | 0Ω | 0V | 0 |
| Center (50%) | 5kΩ | 5kΩ | 2.5V | ~512 |
| Full Clockwise | 0Ω | 10kΩ | 5V | 1023 |