What frequency corresponds to ultrasonics?

Ultrasonics refers to sound waves that have frequencies above the audible range for humans, which typically extends up to around 20 kilohertz (20,000 cycles per second). When considering ultrasonic frequencies, they are generally defined as being above 20 kilohertz. In the context of the options provided, frequencies described as "over 500 kilocycles per second" (or 500,000 hertz) would certainly fall well within the ultrasonic range.

Understanding that ultrasonic sound waves possess various applications, particularly in the medical and veterinary fields (e.g., ultrasound imaging), emphasizes the relevance of this definition. Frequencies over 500 kilocycles per second are indeed well above the standard ultrasonic threshold, making this option the correct interpretation regarding ultrasonics.