Question #e9ce6

1 Answer
José Roberto Pereira
Oct 18, 2015

With an infrared sensor.

Explanation:

It can be detected with an infrared sensor.

A simple way to do it is using your celular phone camera.

Point it to a remote control (TV, DVD...) and press a key in the control. You will see it lighting in the camera screen.

Related questions
Impact of this question
5827 views around the world
You can reuse this answer
Creative Commons License