Non-Destructive Testing (NDT) Practice Test

Which two factors primarily affect attenuation in materials?

1. Hardness and density

2. Temperature and pressure

3. Absorption and scattering

4. Thickness and coating

The correct answer is: Absorption and scattering

Attenuation in materials refers to the reduction in intensity of a wave as it passes through a medium. This process is primarily influenced by absorption and scattering, making this choice the most accurate. Absorption occurs when energy from the wave is taken up by the material, contributing to a decrease in the wave's amplitude. Scattering involves the redirection of wave energy due to irregularities or particles within the material, which can further diffuse the intensity of the wave as it travels. Both factors are critical when evaluating how waves behave in different materials, especially in non-destructive testing where sound waves, electromagnetic waves, or other forms of energy are used to assess material integrity or detect flaws. Considering the other factors, hardness, density, temperature, pressure, thickness, and coating can influence various properties of the material, such as strength, elasticity, and thermal characteristics, but they do not directly impact the attenuation mechanism in the same fundamental way as absorption and scattering. Therefore, focusing specifically on the mechanisms that influence the reduction of energy in waves clearly identifies absorption and scattering as the primary factors affecting attenuation.