What term refers to the difference between actual instrument output and expected output based on a calibration curve?

The term that refers to the difference between actual instrument output and expected output based on a calibration curve is known as nonlinearity. Nonlinearity occurs when the response of an instrument varies from what is predicted by a linear model or calibration curve. In the context of Eddy Current Testing, this is crucial because it can significantly affect the accuracy and reliability of the measurements obtained from the test. Nonlinear responses can arise from various factors, including the sensor design, the material characteristics, and the operational conditions.

This concept is particularly important for technicians and engineers using Eddy Current Testing, as it helps them understand how to interpret test results accurately. By recognizing and addressing nonlinearity, they can ensure that their measurements are consistent and reflective of the actual conditions of the test material. In Eddy Current Testing, ensuring high linearity in instrument response is essential for reliable defect detection and characterization.