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If an LED connected to a Raspberry Pi GPIO pin is controlled with PWM set to a 75% duty cycle, what will be the perceived brightness of the LED?

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Raspberry Pi - PWM Output
If an LED connected to a Raspberry Pi GPIO pin is controlled with PWM set to a 75% duty cycle, what will be the perceived brightness of the LED?
AThe LED will be off most of the time and appear very dim.
BThe LED will be fully on with no brightness change.
CThe LED will flicker rapidly but appear fully off.
DThe LED will be at approximately three-quarters of its maximum brightness.
Step-by-Step Solution
Solution:

  1. Step 1: Understand duty cycle meaning

    75% duty cycle means the signal is ON 75% of the time.

  2. Step 2: Effect on LED brightness

    The LED receives power 75% of the time, so it appears about 75% as bright as fully ON.

  3. Final Answer:

    The LED will be at approximately three-quarters of its maximum brightness. -> Option D

  4. Quick Check:

    Does 75% duty cycle mean 75% brightness? Yes. [OK]
Quick Trick: Duty cycle % ≈ LED brightness % [OK]
Common Mistakes:
  • Confusing duty cycle with frequency
  • Expecting flicker instead of steady brightness
  • Assuming LED is fully off or on only

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