How do the mirrors in the hotel know if they are monitored?

Turn off the light in the room, turn on the camera of the mobile phone and aim the camera at the mirror. If there is monitoring behind the mirror, you will see the bright spot of infrared light.

Infrared is an electromagnetic wave with a wavelength between microwave and visible light, and an invisible light with a wavelength between 760 nm and 1 mm, which is longer than red light.

Anything above absolute zero (-273. 15℃) can produce infrared rays. Modern physics calls it thermal rays. Medical infrared rays can be divided into near infrared rays and far infrared rays. It contains heat energy, and the heat of the sun is mainly transmitted to the earth through infrared rays.

Extended data:

Location of general equipment for hotel monitoring:

1, installed on the smoke detector on the ceiling;

2. At the air outlet of the air conditioner;

3. Oil on the bed. Painting or decoration;

4. Near the TV;

5, the bottom of the table tip.

People's Daily Online-It is not unnecessary to ban hotel room monitoring.