# Bit Of Trivia

**URL:** <https://community.cartalk.com/t/bit-of-trivia/183318>\
**Category:** General Discussion\
**Created:** [March 30, 2022, 2:06pm UTC](https://community.cartalk.com/t/bit-of-trivia/183318 "2022-03-30T14:06:13Z")\
**Posts on this page:** 1\
**Page:** 4

<div class="post-metadata">

**Author:** ![George\_San\_Jose1](https://avatars.discourse-cdn.com/v4/letter/g/e5b9ba/32.png) [@George\_San\_Jose1](https://community.cartalk.com/u/George_San_Jose1)\
**Post date:** [April 6, 2022, 11:29pm UTC](https://community.cartalk.com/t/bit-of-trivia/183318/61 "2022-04-06T23:29:50Z")

</div>

I asked Google “How do motion sensors work?”.

_Active ultrasonic sensors emit ultrasonic sound waves at a frequency above the range of human hearing. These waves bounce off objects in the immediate vicinity and return to the motion sensor. A transducer within the sensor acts as a waypoint for the signal—it sends the pulse and receives the echo_

[Previous page](https://community.cartalk.com/t/bit-of-trivia/183318.md?page=3)