In ultrasonic testing, which of the following is true regarding the echo received from a discontinuity?

The correct selection indicates that the echo provides information about the size and nature of the flaw. In ultrasonic testing, when a sound wave is transmitted into a material, it encounters various discontinuities such as cracks, voids, or inclusions. When these waves hit a discontinuity, some of the energy is reflected back as an echo.

The characteristics of this echo—such as its amplitude, duration, and the time it takes for the echo to return—can give valuable insights into the size and type of the flaw. For instance, a larger flaw may generate a stronger echo, while the pattern of the echo can indicate the nature of the discontinuity. Different types of flaws will reflect sound waves differently based on their geometry and material properties, leading to distinct echo signatures.

Understanding this relationship between the echo and the flaw allows technicians to make informed assessments regarding the integrity of the tested material, which is a crucial aspect of nondestructive testing.