What property of mirrors allows them to change the direction of light?
a) Refraction
b) Diffraction
c) Reflection
d) Dispersion
Which type of mirror provides an enlarged field of view of the reflected image?
a) Flat
b) Convex
c) Concave
d) Parabolic
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
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
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
Which type of prism deflects light rays by 90 degrees?
a) Right angle prism
b) Porro prism
c) Convex prism
d) Concave prism
What is the angle above which all light is reflected known as?
a) Incidence angle
b) Refractive angle
c) Critical angle
d) Reflection angle
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
How do prisms separate the frequencies of a chromatic light source?
a) By refraction
b) By diffraction
c) By dispersion
d) By reflection
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
What is the most frequent reason for reduced vision acuity?
a) Glaucoma
b) Cloudy ocular media
c) Uncorrected refractive error
d) Macular degeneration
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
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%
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
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
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
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
Which condition is NOT listed as a reason for reduced vision acuity?
a) Glaucoma
b) Scarred cornea
c) Diabetic retinopathy
d) Nearsightedness
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
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
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
Which type of light source is ineffective during direct visual testing but recommended for automated inspection?
a) Incandescent
b) Luminescent
c) Polarized
d) Solar
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
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
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
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
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
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
What is the primary characteristic of coherent light?
a) Broad spectrum
b) Non-directional propagation
c) Parallel alignment of rays
d) Random phase coherence
Which optical technique uses polarized light to measure interference patterns for assessing test objects?
a) Diffraction
b) Refraction
c) Birefringence
d) Dispersion
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
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
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
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
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
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
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
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
Which tool is recommended for visually detecting surface cracks in welding?
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