A quality assurance engineer at a frying pan company is asked to qualify a new l

Question

A quality assurance engineer at a frying pan company is asked to qualify a new line of nonstick-coated frying pans. The coating needs to be 1.00 mm thick. One method to test the thickness is for the engineer to pick a percentage of the pans manufactured, strip off the coating, and measure the thickness using a micrometer. This method is a destructive testing method. Instead, the engineer decides that every frying pan will be tested using a nondestructive method. An ultrasonic transducer is used that produces sound waves with a frequency of f=25kHz. The sound waves are sent through the coating and are reflected by the interface between the coating and the metal pan, and the time is recorded. The wavelength of the ultrasonic waves in the coating is 0.076 m. What should be the time recorded if the coating is the correct thickness (1.00 mm)? Can u please explain in details the steps.

Explanation / Answer

frequency =25*103 hz and wavelength=0.076 m

Velocity will be = 1900 m/s

total time will be =2*thickness of coating/velocity=2*0.001/1900= 1.0526*10-6 seconds

its simple formula t=distance/velocity

here distance will be twice of thickness of coating.

because the wave travel twice the coating, one time for entering another time for existing thus 2*coating thickness

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