NCCER Millwright Practice Exam

What method does radiography use to project an image onto a detector or film?

1. Sound waves

2. Visible light

3. Source of penetrating radiation

4. Infrared radiation

The correct answer is: Source of penetrating radiation

Radiography utilizes a source of penetrating radiation to project an image onto a detector or film. This method involves the use of high-energy radiation, such as X-rays or gamma rays, which can penetrate various materials. When this radiation passes through an object, it interacts differently with the different densities and compositions of materials, resulting in variations in radiation intensity that reaches the detector or film. The areas where the radiation penetrates more easily appear darker on the film, while denser areas that absorb more radiation appear lighter. This differential absorption creates a detailed image that can reveal structural integrity and any flaws within the object being examined. The precise nature of the penetrating radiation allows for effective imaging of internal features without the need for physical disassembly. Other methods mentioned, such as sound waves, visible light, and infrared radiation, do not provide the same level of penetration or imaging capability for internal structures in materials, making them unsuitable for radiographic testing.