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CGSB EDDY CURRENT TESTING (ET) LEVEL 1
QUESTIONS AND CORRECT ANSWERS (VERIFIED
ANSWERS) Q & A 2026 |INSTANT DOWNLOAD PDF
1. What is the principle of eddy current testing? A. Magnetic particle attraction B. Electromagnetic induction C. Radiation absorption D. Ultrasonic reflection Rationale: Eddy current testing is based on Faraday’s law of electromagnetic induction. Correct Answer: B 2. Eddy currents are induced in which type of material? A. Non-conductive materials B. Magnetic materials only C. Conductive materials D. Plastic materials Rationale: Eddy currents require electrical conductivity. Correct Answer: C 3. Which law governs eddy current formation?
A. Ohm’s Law B. Newton’s Law C. Faraday’s Law D. Boyle’s Law Rationale: Changing magnetic fields induce currents per Faraday’s Law. Correct Answer: C
4. Eddy current testing is mainly used for: A. Plastic welding B. Surface and near-surface defect detection C. Internal void detection in concrete D. Soil testing Rationale: Eddy currents penetrate only shallow depths. Correct Answer: B 5. The depth of penetration depends on: A. Color of material B. Frequency and conductivity C. Shape of object D. Operator skill only Rationale: Higher frequency reduces penetration depth. Correct Answer: B
9. Eddy current testing is a: A. Mechanical test B. Radiographic test C. Non-destructive test D. Destructive test Rationale: It does not damage the material. Correct Answer: C 10. The primary unit of frequency is: A. Tesla B. Hertz C. Ohm D. Newton Rationale: Frequency is measured in Hertz (Hz). Correct Answer: B 11. Eddy currents are strongest at: A. Material center B. Surface C. Entire volume equally D. Corners only Rationale: Due to skin effect, currents are surface concentrated. Correct Answer: B
12. Which is NOT a factor affecting eddy current testing? A. Conductivity B. Permeability C. Operator age D. Frequency Rationale: Operator age has no physical effect. Correct Answer: C 13. Probe in ET is also called: A. Coil B. Magnet C. Transducer D. Radiator Rationale: The coil generates and receives signals. Correct Answer: A 14. Lift-off effect occurs when: A. Probe touches surface B. Probe moves away from surface C. Current increases D. Material melts Rationale: Distance affects signal strength. Correct Answer: B
18. Conductivity is measured in: A. Siemens per meter B. Ohms C. Volts D. Watts Rationale: Conductivity is S/m. Correct Answer: A 19. Permeability affects: A. Light reflection B. Magnetic field distribution C. Weight D. Density Rationale: Magnetic properties influence eddy currents. Correct Answer: B 20. Eddy current testing cannot detect: A. Surface cracks B. Near surface flaws C. Deep internal voids D. Conductivity variations Rationale: Limited penetration depth. Correct Answer: C
21. The output signal is displayed on: A. Oscilloscope B. Thermometer C. Barometer D. Speedometer Rationale: Signals are visualized electrically. Correct Answer: A 22. Which is a disadvantage of ET? A. Fast results B. Requires conductive materials C. Non-contact method D. High sensitivity Rationale: Cannot test non-conductors. Correct Answer: B 23. Eddy current testing is commonly used in: A. Aviation industry B. Agriculture C. Cooking D. Textile design Rationale: Aircraft inspection is a key application. Correct Answer: A
27. Eddy currents are AC in nature because: A. Voltage is DC B. Magnetic field changes C. Material is hot D. Coil is broken Rationale: AC induces changing fields. Correct Answer: B 28. Calibration standard is used to: A. Paint surface B. Verify equipment accuracy C. Increase speed D. Reduce cost Rationale: Ensures correct readings. Correct Answer: B 29. Signal amplitude depends on: A. Defect size B. Color C. Weight D. Length only Rationale: Larger defects produce stronger signals. Correct Answer: A
30. Noise in ET refers to: A. Useful signal B. Unwanted signal interference C. Heat D. Light Rationale: Random disturbances affect readings. Correct Answer: B 31. Conductivity decreases with: A. Lower temperature B. Higher temperature C. More polish D. Shape change Rationale: Resistance increases with temperature. Correct Answer: B 32. Lift-off effect is more significant in: A. Contact probes B. Non-contact probes C. Radiography D. Welding Rationale: Distance changes signal strength. Correct Answer: B
36. Eddy currents produce: A. Heat B. Magnetic field opposing original field C. Light D. Sound only Rationale: Lenz’s law applies. Correct Answer: B 37. Lenz’s law states: A. Current increases temperature B. Induced current opposes cause C. Gravity increases current D. Light bends current Rationale: Opposition to change in flux. Correct Answer: B 38. Probe lift-off increases: A. Signal strength B. Noise and error C. Accuracy D. Conductivity Rationale: Distance reduces accuracy. Correct Answer: B
39. Which is NOT a type of probe? A. Surface probe B. Bobbin probe C. Radiographic probe D. Encircling coil Rationale: Radiography uses X-rays. Correct Answer: C 40. Encircling coils are mainly used for testing: A. Flat plates B. Conductive rods and wires C. Plastic pipes D. Concrete structures Rationale: Encircling coils surround cylindrical conductive materials. Correct Answer: B 41. Bobbin probes are commonly used for: A. Surface inspection of plates B. Tube internal inspection C. Radiography D. Liquid testing
Rationale: Better conductivity supports stronger currents. Correct Answer: B
45. Ferromagnetic materials generally cause: A. No effect on testing B. Strong interference and reduced penetration C. Perfect accuracy D. Optical reflection Rationale: Magnetic permeability affects eddy current flow. Correct Answer: B 46. The sensitivity of ET depends mainly on: A. Operator speed B. Frequency of excitation C. Color of probe D. Temperature of air only Rationale: Frequency controls penetration and sensitivity. Correct Answer: B 47. Calibration standards are used to: A. Paint test samples B. Verify instrument accuracy C. Increase conductivity D. Reduce defects
Rationale: Standards ensure reliable measurement. Correct Answer: B
48. Surface roughness affects ET by: A. Increasing signal clarity B. Increasing noise C. Removing defects D. Increasing conductivity Rationale: Irregular surfaces distort signals. Correct Answer: B 49. Eddy current testing cannot detect: A. Surface cracks B. Near-surface defects C. Deep internal voids D. Conductivity changes Rationale: Limited penetration depth restricts detection. Correct Answer: C 50. Coil impedance is affected by: A. Material properties B. Color C. Shape of operator D. Lighting conditions
Rationale: They measure absolute signal response. Correct Answer: B
54. Eddy currents are strongest at: A. Center of thick material B. Surface C. Corners only D. Edges only Rationale: Skin effect concentrates currents at surface. Correct Answer: B 55. The skin effect is caused by: A. Gravity B. AC current distribution C. Light absorption D. Heat transfer Rationale: Alternating current repels inward flow. Correct Answer: B 56. Increasing frequency results in: A. Deeper penetration B. Shallower penetration C. No change D. Material melting
Rationale: Higher frequency reduces penetration depth. Correct Answer: B
57. Lower frequency is used to detect: A. Surface only B. Deeper flaws C. Air gaps D. Plastic defects Rationale: Lower frequency penetrates deeper. Correct Answer: B 58. Conductivity is measured in: A. Ohms B. Siemens per meter C. Volts D. Tesla Rationale: SI unit of conductivity is S/m. Correct Answer: B 59. Magnetic permeability affects: A. Electrical brightness B. Field distribution C. Weight D. Temperature only
