Magnetic Particle Inspection Level 1 Practice Exam

How does direct current demagnetizing compare to alternating current demagnetization?

1. Less complete and effective

2. Equally effective

3. More complete and effective

4. Not effective

The correct answer is: More complete and effective

Direct current demagnetizing is considered more complete and effective compared to alternating current demagnetization due to the inherent properties of the currents used in each method. In direct current demagnetizing, a steady flow of current is applied to the object being demagnetized in a manner that allows for a controlled reduction of the magnetic field. The process typically involves reducing the current gradually or using coil techniques where the object is moved through a magnetic field that steadily diminishes. This allows for a thorough and gradual reduction of the magnetism within the material. On the other hand, alternating current (AC) demagnetization, while useful, generally introduces a changing magnetic field that can often lead to residual magnetism. The alternating nature means that the field continually reverses, which can prevent a complete reduction of the magnetic properties as effectively as direct current would. This can result in some magnetism remaining in the material after the process is completed. Thus, the methodology and effects of direct current make it a more complete and effective method for demagnetization, which is why this choice is the most accurate in comparing the two techniques.