MEMS and sensors

Which sensor does a smartphone use to automatically adjust screen brightness to its surroundings?

  1. ABarometric pressure sensor
  2. BIlluminance (ambient light) sensor
  3. CGyroscope
Show answer and explanation

Answer: B. Illuminance (ambient light) sensor

An ambient light sensor measures surrounding brightness with a photodiode or similar. Filtered to resemble the sensitivity of the human eye, it lets the phone adjust screen brightness to the measured light, balancing visibility and power saving.

  • A. A pressure sensor estimates altitude changes and similar from air pressure.
  • B. Correct. It measures the surrounding brightness.
  • C. A gyroscope measures rotation rate (angular velocity).
Practice this topic Back to topic

More MEMS and sensors questions

  1. What is the general principle of the sensor a smartphone uses to turn off the screen when your face approaches during a call, preventing accidental touches?
  2. What is the driving principle of the "comb-drive" structure used as a MEMS actuator?
  3. Which device uses acoustic waves traveling along the surface of a piezoelectric substrate and serves as a high-frequency filter in smartphones and similar?
  4. Which sensor, widely used in motion sensors that turn on lights when a person approaches, uses a material that generates charge when its temperature changes?
  5. Which is an example of MEMS "energy harvesting"?