Ultrasonic cleaners commonly use a steady frequency of 40kHz in water.
Given: speed of sound in water =1480ms−1 and in brass =4700ms−1.
(i) Calculate the wavelength of the ultrasonic wave in water at 40kHz.
(ii) Cavitation bubbles form most effectively when their diameter is roughly one-third of the wavelength of the driving sound. Compute the bubble diameter that would resonate best in water at this frequency.
(iii) If the same 40kHz transducer is used to inspect a brass component, determine the corresponding wavelength in brass. Comment on whether the cleaning action based on cavitation bubbles would be stronger, weaker, or approximately the same in brass compared with water, giving a reason for your answer.