ABO OPTICAL EXAM 2023 QUESTIONS WITH CORRECT ANSWERS

Light falling on the front surface of a spectacle lens is: A) partially reflected, partially absorbed and the remainder refracted B) partially reflected and the remainder refracted C) partially absorbed and the remainder refracted D) totally refracted - Answer- A) partially reflected, partially absorbed and the remainder refracted Concave mirror: A) can focus parallel incident rays to form a real image B) can focus parallel incident Rays to form a virtual image C) always produce inverted images of real objects D) produces virtual images smaller than the real object. - Answer- A) can focus parallel incident rays to form a real image Reflection is reduced by depositing a layer of magnesium fluoride on the lens surface. It has a thickness of: A) 1/2 the wave length of white light B) 1/4 the wave length of white light C) 1/2 the wave length of blue-violet light D) the wave length of yellow light - Answer- D) the wave length of yellow light White light is broken into its components colors when it is: A) diffracted B) refracted C) reflected D) diffracted or refracted - Answer- D) diffracted or refracted Anti reflective coating of a lens is based on the principle of: A) diffraction B) reflection C) interference D) reflection and interference - Answer- D) reflection and interference To the viewer the image seen in a plane mirror appears to be: A) inverted B) 1/2 as large as the object C) twice as large as the object D) as far behind the mirror as the object is in front of it. - Answer- D) as far behind the mirror as the object is in front of it. The velocity of light is least in: A) air B) polycarbonate C) water D) flint glass - Answer- D) flint glass What is prism in simplest terms? - Answer- A wedge of transparent material used to disperse and or deviate light. Define Phoria - Answer- A TENDENCY to cross (not cosmetic) Define Tropia - Answer- An actual "crossing" very noticeable. Crown glass index - Answer- 1.523 Which lens has more aberrations? A) Flint Glass B) Crown Glass - Answer- A) Flint Glass Plus Lenses can be A) Convex B) Concave C) Both - Answer- A) Convex (plus lenses can be equiconvex, Flat convex, Double covex/biconvex or Meniscus) Minus Lenses Can Be A) Convex B) Concave C) Both - Answer- B) Concave (minus lenses can be equiconcave, flat concave, double concave/bioconcave or meniscus) Nominal power equation - Answer- Dn= D1+D2. (Lens power (Dn) equals the power of the front surface (D1) and the power of the back surface (D2) of the lens) The wavelength of the infrared waves in the electromagnetic spectrum are: A) longer than visible red light waves B) shorter than the visible red waves C) 550 nanometers D) between 380 and 780 nanometers - Answer- A) longer than visible red light waves The Geneva Lens Measure is calibrated for a refractive index of: A) crown glass B) CR-39 C) 1.530 D) 1.234 - Answer- C) 1.530 A lens made from 2 Convex surfaces: A) corrects myopia B) corrects astigmatism C) makes objects appear smaller D) has against motion - Answer- D) has against motion