Which frequency is ultrasound?

Which frequency is ultrasound?

• A. 2000 Hz
• B. 20 Hz
• C. 2 MHz
• D. 200 Hz

Answer: (C)

Ultrasound refers to sound waves with frequencies above the upper limit of human hearing. Humans can hear up to about 20 kHz, so any frequency higher than that is considered ultrasound. Among the given options, 2 megahertz equals 2,000,000 Hz, which is far above 20,000 Hz. That puts it squarely in the ultrasound range, commonly used in medical imaging (often around 1–15 MHz). The other choices—2000 Hz, 20 Hz, and 200 Hz—are all within or below the audible range for humans, so they are not ultrasound.

Ultrasound refers to sound waves with frequencies above the upper limit of human hearing. Humans can hear up to about 20 kHz, so any frequency higher than that is considered ultrasound. Among the given options, 2 megahertz equals 2,000,000 Hz, which is far above 20,000 Hz. That puts it squarely in the ultrasound range, commonly used in medical imaging (often around 1–15 MHz). The other choices—2000 Hz, 20 Hz, and 200 Hz—are all within or below the audible range for humans, so they are not ultrasound.