ABO OPTICAL EXAM

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