Physics for IGCSE & O level - Waves And Sounds (Section 6 - No. 18)

What is the wavelength of the ultrasound in water, if the frequency is 40 kHz and the speed of sound in water is 1400 m/s?

0.035 m

0.07 m

0.14 m

0.28 m

Using the wave equation (speed = frequency * wavelength): wavelength = speed/frequency = 1400 m/s / 40000 Hz = 0.035 m