Non-Destructive Testing (NDT) Practice Test

Which method best describes the action of ultrasonic waves in flaw detection?

1. Reflection and refraction

2. Absorption and transmission

3. Diffraction and interference

4. Resonance and vibration

The correct answer is: Reflection and refraction

Ultrasonic waves in flaw detection are primarily characterized by the processes of reflection and refraction. When an ultrasonic wave is introduced into a material, it travels through the medium and interacts with any internal flaws or discontinuities. When the wave encounters a flaw—such as a crack or void—it reflects back to the sensor, creating echoes that can be analyzed. The phenomena of refraction occur when ultrasonic waves travel from one material to another, changing speed and direction, which allows for the inspection of different layers or interfaces within a material. Together, these two actions—reflection and refraction—are fundamental to the operation of ultrasonic testing, as they enable technicians to assess the integrity of materials by interpreting the resulting signals. The other methods mentioned, while they may play roles in broader contexts of wave behavior, do not primarily define the flaw detection capabilities of ultrasonic testing. Absorption and transmission are more relevant to understanding how materials attenuate sound waves rather than detecting flaws. Diffraction and interference relate more to wave behaviors that may not be directly utilized to identify flaws in a practical NDT setting. Resonance and vibration mainly pertain to how materials respond to certain frequencies but do not directly indicate the presence of flaws in the same way that reflection and refraction do