An ultrasonic motion sensor uses two piezoelectric transducers that emit continuous sound waves. One transducer produces a wave at 40.000 kHz, and the other at 40.010 kHz. The two outputs are directed toward the same point, where a microphone connected to an oscilloscope records the combined signal.
(a) Express the two operating frequencies in hertz (Hz) rather than kilohertz (kHz).
(b) Calculate the rate at which the microphone signal reaches maximum intensity.
(c) Determine the time interval between successive maxima recorded on the oscilloscope trace.