Non-Destructive Testing (NDT) 2025 – 400 Free Practice Questions to Pass the Exam

The transducer with the least amount of divergence is determined by the frequency and the corresponding wavelength of the ultrasound waves produced. In general, higher frequency transducers have shorter wavelengths, which leads to more focused ultrasound beams and thus less divergence.

In this context, the 10MHz longitudinal transducer stands out because it operates at a higher frequency compared to the other options presented. The higher frequency induces a more tightly focused beam, improving resolution and enabling better detection of smaller flaws with reduced scattering. This characteristic implies that the sound waves emanate in a more concentrated manner, resulting in less divergence as they propagate through the material.

The other frequencies, while effective in their own right, will result in beams that spread out more as they travel through the material, leading to greater divergence. Lower frequency transducers like the 2.5MHz and the 5MHz produce longer wavelengths, which naturally create a wider beam divergence, making it harder to concentrate the sound energy over a specific point. The 20MHz transducer, despite its high frequency, might also introduce other practical limitations in certain applications.

Therefore, the 10MHz longitudinal transducer is recognized for having the least divergence, providing an optimal balance of penetration and resolution in non-destructive testing scenarios.