What are light sensors in a mobile phone?

Answer 1

The ambient light sensor is a power saving feature. It measures the luminance value of the light (think a camera with a very low resolution that can only measure brightness)

The darker the environment, the less backlight you need so it automatically lower the backlight brightness.

Here is a picture of one that you may find in a smartphone: i.imgur.com/eWPH9.jpg

If you would like to know the info that your light sensor is picking up (and have an android phone), then you can download the phone tester app then look at the sensor data. play.Google.com/store/apps/details?id=com.mtorres.phonetester&hl=en

Answer 2

The phone's camera could be considered a light sensor, but you could be referring to the light sensor, which tells the phone to dim the screen when the surroundings are dark. This is achieved through a photocell or photosensor. In simple terms, they are variable resistors, whose resistance is proportional to the amount of light hitting them.