ASNT (Visual Testing) VT Level III Questions- Answers

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  1. What property of mirrors allows them to change the direction of light?
    • a) Refraction
    • b) Diffraction
    • c) Reflection
    • d) Dispersion
  2. Which type of mirror provides an enlarged field of view of the reflected image?
    • a) Flat
    • b) Convex
    • c) Concave
    • d) Parabolic
  3. Where is the reflecting focal point of a concave or spherical mirror located?
    • a) In front of the mirror
    • b) Behind the mirror
    • c) At the center of the mirror
    • d) At the top of the mirror
  4. What happens to light when it is projected onto a spherical mirror normal to the curve of the surface?
    • a) It is absorbed by the mirror
    • b) It is refracted away from the mirror
    • c) It is focused slightly in front of the mirror
    • d) It passes through the mirror unaffected
  5. How does a concave mirror reflect light when a point light source is placed at its focal point?
    • a) It reflects the light back towards the source
    • b) It refracts the light away from the source
    • c) It reflects the light parallel to the normal of the curve
    • d) It focuses the light at a point in front of the mirror
  6. Which type of prism deflects light rays by 90 degrees?
    • a) Right angle prism
    • b) Porro prism
    • c) Convex prism
    • d) Concave prism
  7. What is the angle above which all light is reflected known as?
    • a) Incidence angle
    • b) Refractive angle
    • c) Critical angle
    • d) Reflection angle
  8. What is the primary function of a porro prism?
    • a) To produce a 90 degree reflection
    • b) To separate frequencies of a chromatic light source
    • c) To change the orientation of the image produced by light rays
    • d) To provide an enlarged field of view of the reflected image
  9. How do prisms separate the frequencies of a chromatic light source?
    • a) By refraction
    • b) By diffraction
    • c) By dispersion
    • d) By reflection
  10. Why do the higher frequency portions of the spectrum emerge from the base of the prism?
    • a) Because the refractive indices of the materials are higher at the base
    • b) Because the refractive indices of the materials are lower at the base
    • c) Because the index of refraction changes with the frequency of the light
    • d) Because the angle of incidence is greater at the base
  11. What is the most frequent reason for reduced vision acuity?
    • a) Glaucoma
    • b) Cloudy ocular media
    • c) Uncorrected refractive error
    • d) Macular degeneration
  12. How is vision conventionally graded?
    • a) By measures of contrast sensitivity
    • b) By the size of the visual objects
    • c) By measures of visual acuity
    • d) By the brightness of the background
  13. What is the typical contrast percentage for a vision acuity chart with black letters?
    • a) Less than 20%
    • b) Between 50% to 60%
    • c) Greater than 85%
    • d) Exactly 100%
  14. What is contrast sensitivity a better predictor of, compared to vision acuity?
    • a) Brightness perception
    • b) Object size perception
    • c) Functional vision performance
    • d) Color perception
  15. At what spatial frequencies is the contrast sensitivity of the normal visual system highest?
    • a) Below 2 cycles per degree
    • b) Between 6 to 8 cycles per degree
    • c) Between 2 to 6 cycles per degree
    • d) Above 8 cycles per degree
  16. Which method presents letters of constant size with decreasing contrast to measure contrast sensitivity?
    • a) Pelli-Robson ™ letter sensitivity chart
    • b) Weber contrast method
    • c) Michelson contrast method
    • d) Contrast threshold method
  17. What does a difference in far vision acuity versus near vision acuity indicate?
    • a) Need for cataract surgery
    • b) Need for glaucoma treatment
    • c) Potential refractive correction benefit
    • d) Development of macular degeneration
  18. Which condition is NOT listed as a reason for reduced vision acuity?
    • a) Glaucoma
    • b) Scarred cornea
    • c) Diabetic retinopathy
    • d) Nearsightedness
  19. What is the angular measure of the smallest detail that can be resolved when presented with high contrast?
    • a) Vision threshold
    • b) Visual acuity
    • c) Spatial frequency
    • d) Contrast threshold
  20. What aspect of the visual system does contrast sensitivity primarily depend on?
    • a) Lens curvature
    • b) Retinal pigment density
    • c) Size of the pupil
    • d) Neural processing
  21. What is the goal when choosing lighting for automated inspection and machine vision applications?
    • a) To increase the brightness of the environment
    • b) To decrease the contrast between discontinuities
    • c) To optimize contrast and reduce signal processing complexity
    • d) To minimize the spectral sensitivity of sensors
  22. Which type of light source is ineffective during direct visual testing but recommended for automated inspection?
    • a) Incandescent
    • b) Luminescent
    • c) Polarized
    • d) Solar
  23. What is critical in automated inspection due to light sensors’ limited ability to adapt to differing levels of illumination?
    • a) Consistent illumination
    • b) Dynamic illumination
    • c) Variable illumination
    • d) Intermittent illumination
  24. Which characteristic of a test material determines the type of lighting geometry and light source for inspection?
    • a) Reflective, absorptive, and transmissive characteristics
    • b) Temperature and pressure
    • c) Electrical conductivity
    • d) Chemical composition
  25. What type of light source is commonly used for inspecting nonselective absorptive materials?
    • a) Condenser reflector
    • b) Spot projector
    • c) Diffuse light source
    • d) Collimated light source
  26. Which lighting technique floods the area of interest with light to minimize shadow formation?
    • a) Side illumination
    • b) Front illumination
    • c) Back illumination
    • d) Top illumination
  27. Which type of light source is characterized by emission due to thermal excitation of atoms or molecules?
    • a) Solar
    • b) Luminescent
    • c) Incandescent
    • d) Coherent
  28. How is luminescent light different from incandescent light sources?
    • a) It emits light without thermal excitation
    • b) It emits light with a broader spectrum
    • c) It emits light with a higher degree of phase coherence
    • d) It emits light with a more monochromatic nature
  29. What is the primary characteristic of coherent light?
    • a) Broad spectrum
    • b) Non-directional propagation
    • c) Parallel alignment of rays
    • d) Random phase coherence
  30. Which optical technique uses polarized light to measure interference patterns for assessing test objects?
    • a) Diffraction
    • b) Refraction
    • c) Birefringence
    • d) Dispersion
  31. What is the term used to describe discontinuities formed during the metal casting process due to imperfect fusion between two streams of metal?
    • a) Cold Shut
    • b) Hot Tears
    • c) Blowholes
    • d) Porosity
    • Answer: a) Cold Shut
  32. Which type of discontinuity may result from uneven cooling in thin sections or corners that adjoin heavier masses of metal?
    • a) Cold Shut
    • b) Pipe
    • c) Hot Tears
    • d) Blowholes
    • Answer: c) Hot Tears
  33. Gas porosities in castings are caused by the accumulation of gas bubbles during solidification. What term describes the non-metallic inclusions usually found in ferrous alloys?
    • a) Cold Shut
    • b) Hot Tears
    • c) Blowholes
    • d) Nonmetallic Inclusions
    • Answer: d) Nonmetallic Inclusions
  34. What type of discontinuity may appear as seams in the rolled ingot and can be conical, wide at the surface, and tapering internally?
    • a) Cold Shut
    • b) Pipe
    • c) Hot Tears
    • d) Blowholes
    • Answer: d) Blowholes
  35. What is the term used to describe the rounded cavities caused by the accumulation of gas bubbles in molten metal as it solidifies?
    • a) Cold Shut
    • b) Pipe
    • c) Hot Tears
    • d) Porosity
    • Answer: d) Porosity
  36. What is undercut in welding?
    • a) A groove formed at the toe or root of a weld
    • b) The complete filling of the root of the weld joint with weld metal
    • c) The melting away of base metal at the root of a weld
    • d) The reduction of base metal thickness due to excessive weld metal
    • Answer: c) The melting away of base metal at the root of a weld
  37. Which standard specifies that undercut should be less than 0.8 mm deep in completed welds?
    • a) AWS D1
    • b) ASME Boiler and Pressure Vessel Code
    • c) ASTM International
    • d) ISO 9001
    • Answer: b) ASME Boiler and Pressure Vessel Code
  38. What is the consequence of inadequate joint penetration in welding?
    • a) Increase in base metal thickness
    • b) Improved fatigue strength of the joint
    • c) Reduction in joint strength, particularly fatigue strength
    • d) Enhancement of joint ductility
    • Answer: c) Reduction in joint strength, particularly fatigue strength
  39. Which tool is recommended for visually detecting surface cracks in welding?
    • a) High-power microscope
    • b) 5× magnifying lens
    • c) Ultrasonic testing device
    • d) Infrared camera
    • Answer: b) 5× magnifying lens
  40. What causes arc strikes in welding?
    • a) Poorly connected welding ground clamp
    • b) Insufficient weld metal
    • c) Inadequate base metal thickness
    • d) Lack of joint penetration
    • Answer: a) Poorly connected welding ground clamp

Answers

  1. Answer: c) Reflection
  2. Answer: b) Convex
  3. Answer: a) In front of the mirror
  4. Answer: c) It is focused slightly in front of the mirror
  5. Answer: c) It reflects the light parallel to the normal of the curve
  6. Answer: a) Right angle prism
  7. Answer: c) Critical angle
  8. Answer: d) To provide an enlarged field of view of the reflected image
  9. Answer: c) By dispersion
  10. Answer: c) Because the index of refraction changes with the frequency of the light
  11. Answer: c) Uncorrected refractive error
  12. Answer: c) By measures of visual acuity
  13. Answer: c) Greater than 85%
  14. Answer: c) Functional vision performance
  15. Answer: c) Between 2 to 6 cycles per degree
  16. Answer: a) Pelli-Robson ™ letter sensitivity chart
  17. Answer: c) Potential refractive correction benefit
  18. Answer: d) Nearsightedness
  19. Answer: b) Visual acuity
  20. Answer: d) Neural processing
  21. Answer: c) To optimize contrast and reduce signal processing complexity
  22. Answer: c) Polarized
  23. Answer: a) Consistent illumination
  24. Answer: a) Reflective, absorptive, and transmissive characteristics
  25. Answer: c) Diffuse light source
  26. Answer: b) Front illumination
  27. Answer: c) Incandescent
  28. Answer: d) It emits light with a more monochromatic nature
  29. Answer: c) Parallel alignment of rays
  30. Answer: c) Birefringence

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