Circuits / Getting started
LED with a series resistor
The resistor sets the LED current: I = (V − Vf) / R
Tap a part to see its voltages and currents. It is a model, not a measurement.
Predict, measure, explain
- Predict With 5 V and 330 Ω, how much current flows through the LED?
- Measure Tap the LED. Then change R1 to 1 kΩ and tap it again.
- Explain
Show the answerHide the answer
About 9.8 mA: the resistor takes the 3.2 V the LED leaves. With 1 kΩ it drops to 3.4 mA, and the LED dims.
Parts
- Resistor 330 ΩSearch on Amazon
- Red LEDSearch on Amazon
- Jumper wires × 1Search on Amazon
- BreadboardSearch on Amazon
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