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Potentiometer dimming an LED

The wiper is an adjustable divider: its voltage goes from 0 to the supply

Potentiometer dimming an LED, simulated on a breadboard

Tap a part to see its voltages and currents. It is a model, not a measurement.

Predict, measure, explain

  1. Predict Where does the LED shine brightest: with the knob at one end, in the middle or at the other end?
  2. Measure Move RV1 from one end to the other and tap the LED at each end.
  3. Explain
    Show the answerHide the answer

    At one end the potentiometer adds nothing and the LED gets 9.8 mA; at the other it adds all its 10 kΩ and the LED goes out.

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