To change the wavelength of sound used in testing, which parameter should be adjusted?

The wavelength of sound used in testing is inversely related to the sound wave frequency. This relationship is described by the formula: wavelength = speed of sound / frequency. By adjusting the frequency of the sound wave emitted by the transducer, you can effectively change the wavelength. A higher frequency results in a shorter wavelength, while a lower frequency leads to a longer wavelength. This principle is crucial in nondestructive testing, as different wavelengths can interact with materials in varying ways, affecting the resolution and penetration of the ultrasound waves.

The other options relate to different aspects of the ultrasonic testing process. For instance, adjusting the pulse duration affects the energy and time characteristics of the sound wave rather than its frequency. The transducer angle influences the direction and possibly the intensity of the sound waves but does not affect the wavelength itself. Similarly, the pulsed output power impacts the amplitude of the sound waves rather than altering the frequency or wavelength. Thus, manipulating the sound wave frequency is the key method for changing the wavelength in ultrasonic testing.