63. A wavelength of 0.3 m is produced in air and it travels at a speed of 300 m/s. Then it will be an A.Audible wave B.Infrasonic wave C.Ultrasonic wave D.Microwave
Option A Solution: The formula of frequency is: f = c / ë = wave speed c (m/s) / wavelength ë (m), where f: frequency, c: wave speed, and ë: wavelength. As per the question, f = 300/0.3 = 1000 cycles/ seconds = 1000 Hz = 1 KHz. Sound waves with frequencies above 20 KHz are called Ultrasonic; those below 20 Hz are called Infrasonic. Sound waves with frequencies between 20 Hz to 20,000 Hz are called audible waves.
