When performing eddy current testing, an increase in frequency typically results in what effect regarding penetration depth?

An increase in frequency during eddy current testing results in decreased penetration depth. This is due to the skin effect, where higher frequencies induce eddy currents that are concentrated nearer to the surface of the conductive material being tested. As the frequency increases, the skin depth—the depth below the surface where the current density drops significantly—decreases. Consequently, eddy currents do not penetrate as deeply, leading to decreased penetration depth. This characteristic is crucial to understand, particularly when assessing the suitability of eddy current testing for various applications and material thicknesses. Understanding the impact of frequency on penetration depth allows technicians to select the appropriate testing parameters based on the material and the type of defects they aim to detect.