Resistors
Read colour codes, build a voltage divider, and see why loads and tolerances matter.
Lesson progress
Colour-code workbench
Click a band, then pick its colour.
Band 1 · Digit 1
Value
4.7 kΩ
±5% → 4.46 kΩ to 4.93 kΩ
47 × 102
E12 series
Standard value
E24 series
Standard value
- Output Vout
- 6 V
- 50.0% of Vin
- Loading error ΔV
- —
- no load
- Divider current I1
- 600 µA
- Tolerance range Vout
- ±300 mV
- 5.7 V … 6.3 V
Tolerance: build it 600 times
±5% partsEvery real resistor is slightly off its marked value. This builds the circuit 600 times with randomly varied parts and plots where Vout lands.
Building circuit 0/600…
- Mean
- 6 V
- Spread (σ)
- 0 V
- Within ±1%
- 0%
Loading: Vout vs load resistance
Rth 5 kΩA small load (left) draws a lot of current and pulls Vout down. A large load (right) barely affects it.
The most common part in electronics
Almost every circuit board is covered in resistors. They limit current (as with the LED in the Transistor lab), set voltages (dividers), bias transistors, and pull logic inputs high or low. They are cheap and tough, but each one comes with three practical questions:
- What value is it? Read the colour code.
- How exact is it? Check the tolerance band.
- Can it take the heat? Compare its power with its rating.
This lab covers all three. You will also build the circuit that resistors are most often used for, the voltage divider, and find out why it misbehaves when you connect a load to it.
Try this