NDT Cheat Sheet 2026

The 30 highest-yield NDT facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. Which type of sensor is most commonly used in acoustic emission testing? → Piezoelectric transducer
2. The term for the combined impact of absorption and dispersion is: → Attenuation
3. Increasing the temperature will: → Raise the speed of evaporation of penetrants
4. Demagnetization of a component after magnetic particle testing is crucial in which of the following scenarios? → When the part is a moving component in an assembly, like a bearing.
5. Which of the following material properties has the MOST significant influence on the magnitude and distribution of induced eddy currents? → Electrical Conductivity
6. For water soluble developer, which kind of developer is used? → Form b
7. Other names for longitudinal waves are: → Both Pressure waves and Compressional waves are correct
8. The water-washable penetrant's water content: → Must be checked regularly
9. What is the fundamental principle behind acoustic emission (AE) testing? → Materials release transient elastic waves when undergoing deformation or damage
10. Which of the following is a key safety advantage of using an X-ray generator compared to a gamma-ray source for industrial radiography? → The radiation from an X-ray tube can be turned off completely.
11. Which kind of calibration block is utilized similarly to the small angle-beam block and looks a lot like it? → A DSC block
12. In acoustic emission testing, 'counts' refers to: → The number of times the AE signal crosses the detection threshold
13. Which of the following is a significant disadvantage of using the prod technique for inducing a circular magnetic field? → It has a high risk of causing arc strikes or localized overheating.
14. A couplant is used between an AE sensor and the test surface primarily to: → Ensure efficient transfer of acoustic waves from the surface into the sensor
15. Water soluble developers are made up of the following chemical compounds: → Dissolved in water
16. What is the primary function of a preamplifier in an acoustic emission testing system? → To amplify the small AE sensor signal before transmission to the main amplifier
17. The detection threshold in an AE system is set to: → Exclude background electromagnetic noise while capturing true AE signals
18. The following is the measurement of a defect's signal in relation to other background reflections: → Signal to noise ratio
19. In ultrasonic testing, which wave mode has particle motion perpendicular to the direction of wave propagation and cannot travel through liquids or gases? → Shear waves
20. Which kind of penetrant is less susceptible to cleaning fluid contamination? → Type II
21. Pollution of the penetration tool: → Will change the surface tension and contact angle
22. In a specific substance, the sound speed is: → Is constant
23. When selecting a tracer gas for leak testing, which of the following is a critical property for ensuring high sensitivity and minimizing false readings? → Low background concentration in the atmosphere
24. When increasing the frequency of the transducer in an ultrasonic test, what is the expected effect on the inspection's sensitivity and wavelength? → Sensitivity increases and wavelength decreases.
25. The Kaiser Effect in acoustic emission testing refers to: → The absence of detectable AE until a previously applied stress level is exceeded
26. The Hit Definition Time (HDT) parameter in AE data acquisition is used to: → Determine when an AE hit has ended by timing from the last threshold crossing
27. The reflective surface of the discontinuity must have a diameter at least as long as ________ wavelength in order to provide a fair chance of being detected. → One-half
28. A "High Radiation Area" must be posted where an individual could receive a dose equivalent in excess of: → 100 mrem in 1 hour at 30 cm from the source.
29. Which of the following is a standard unit used to express a leak rate, representing a throughput of gas? → Atmosphere cubic centimeters per second (atm·cm³/s)
30. While utilizing a fluorescent penetrant, the part's surface should have a white light intensity of: → A maximum of 2 foot-candles