How much energy and for what does the sensor consume?

Question

Electronics

Motion sensor for example.
Please explain in simple terms

Answer 1

How much is written in the documentation for the sensor.
For what - for their work.
Not counting the LED indicators of work:
Infrared motion sensor - reading a picture from an IR-sensitive matrix and analyzing the read image in time.
Radio wave motion sensor - radio frequency generation, reception and analysis of the reflected signal
Ultrasonic motion sensor - similarly, only not radio frequency, but ultrasound
Radioisotope smoke sensor - passing current through the ionization chamber and analyzing its
change change analysis
Reed opening sensor - as such, it does not consume current for operation, but current still flows through it (as well as through other sensors) along the signal line to monitor the integrity of the loop.