How can defect size be estimated in VT without instruments?

• A. By comparing the indication to known reference features, using calibrated magnification, or referring to standard defect templates; avoid undocumented measurements.
• B. Random guess.
• C. By measuring with a ruler on the screen.
• D. By the color intensity.

Answer: (A)

Estimating defect size without instruments relies on translating what you see into a known dimension by using reference features and calibrated magnification. By comparing the defect’s apparent size to features on the part with established dimensions, you can infer its real size. If you have calibrated magnification, you know exactly how on-screen measurements map to millimeters, letting you convert the observed size into a precise value. Standard defect templates provide predefined sizes and shapes to match against, giving a consistent, traceable basis for estimation. Together, these approaches yield reliable size estimates without dedicated measuring tools and avoid undocumented measurements that lack traceability. Relying on random guessing, measuring with a ruler on the screen, or judging by color intensity would be unreliable, since they don’t provide a dependable link to actual dimensions.