Answer:
anti-theft alarms. From a technological point of view, anti-theft equipment is based on the emission of the electromagnetic wave by an emitter and its reception by a receiving device. All waves are characterized by the amplitude and frequency they have.
Step-by-step explanation:
In order to generate the alarm, a magnetic field is created between the emitter and the receiver, which when a device whose frequency is equal to that transmitted by the transmitter enters into a state of resonance with it, and through an electronic circuit it is possible to detect and in this way the alarm that can be auditory, visual occurs.
At a lower frequency, electromagnetic waves have a greater capacity for penetration by objects, a lower attenuation of the signal when traversed.