NCIDQ IDFX Practice Exam

Which type of detectors emits a very high frequency sound wave?

1. Infrared detectors

2. Ultrasonic detectors

3. Microwave detectors

4. Audio detectors

The correct answer is: Ultrasonic detectors

Ultrasonic detectors are designed to emit sound waves at frequencies above the range of human hearing, typically above 20 kHz. This high-frequency sound is used in various applications, such as detecting movement or measuring distance, because ultrasonic waves can reflect off objects and enable the detector to sense changes in the environment. The ability to utilize these high frequencies allows for more precise detection and reduces the likelihood of interference from other sounds within the audible range. In contrast, infrared detectors operate using infrared radiation rather than sound waves; they detect changes in heat or movement and are commonly used in motion sensing. Microwave detectors utilize microwave radiation for similar purposes but at different wavelengths. Audio detectors are focused on sounds within the human hearing range and do not operate at the high frequencies characteristic of ultrasonic detectors. Thus, ultrasonic detectors stand out for their unique capability to emit very high frequency sound waves.