Ultrasonic sound is:
A. Sound of frequency less than 20 Hz
B. Sound of frequency more than 20 KHz
C. Sound of frequency 20 Hz to 20000 Hz
D. None of these.
Answer:B
Ultrasonic sound is:
A. Sound of frequency less than 20 Hz B. Sound of frequency more than 20 KHz C. Sound of frequency 20 Hz to 20000 Hz D. None of these.