Physics Ultrasonic have__________________? Options:A. frequency in the audible rangeB. frequency is greater than 20 kHzC. frequency lower than 20 HzD. all of aboveView AnswerB. frequency is greater than 20 kHz Continue Reading Previous: A stationary wave is set up in the air column of a closed pipe. At the closes end of the pipe _____________________?Next: Fundamental frequency of stationary waves in open pipe is ______________ times the frequency in closed pipe?