Which of the following are the types of indications produced during Magnetic Particle Testing?

The types of indications produced during Magnetic Particle Testing (MPT) are classified based on the origins of the magnetic fields that generate those indications. Residual magnetic field-induced indications are formed from the magnetic field that remains in the part once it has been magnetized. This is crucial because it allows for the detection of any discontinuities that may exist within or on the surface of the material.

Yoke-induced indications result from the use of a yoke magnet, which generates a magnetic field that can draw in magnetic particles to reveal defects, while coil-induced indications are created through the application of a magnetic field via inductive coils. Both of these methods are essential in the practical application of MPT, as they ensure a thorough examination by maximizing the effective coverage of the magnetic field on the part being tested.

Understanding these types of indications allows an inspector to accurately interpret the results and identify potential flaws, making the correct option particularly significant in the context of Magnetic Particle Testing practices. The emphasis on residual magnetic field and other induced types underscores the importance of the method's operational principles and how they relate to revealing surface and near-surface defects effectively.