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refractionmore about refraction


  3  definitions  found 
  From  Webster's  Revised  Unabridged  Dictionary  (1913)  [web1913]: 
  Refraction  \Re*frac"tion\  (r?*fr?k"sh?n),  n.  [F.  r['e]fraction.] 
  1.  The  act  of  refracting,  or  the  state  of  being  refracted. 
  2.  The  change  in  the  direction  of  ray  of  light,  heat,  or  the 
  like  when  it  enters  obliquely  a  medium  of  a  different 
  density  from  that  through  which  it  has  previously  moved 
  Refraction  out  of  the  rarer  medium  into  the  denser, 
  is  made  towards  the  perpendicular.  --Sir  I. 
  3.  (Astron.) 
  a  The  change  in  the  direction  of  a  ray  of  light,  and 
  consequently,  in  the  apparent  position  of  a  heavenly 
  body  from  which  it  emanates,  arising  from  its  passage 
  through  the  earth's  atmosphere;  --  hence  distinguished 
  as  atmospheric  refraction,  or  astronomical  refraction. 
  b  The  correction  which  is  to  be  deducted  from  the 
  apparent  altitude  of  a  heavenly  body  on  account  of 
  atmospheric  refraction,  in  order  to  obtain  the  true 
  {Angle  of  refraction}  (Opt.),  the  angle  which  a  refracted  ray 
  makes  with  the  perpendicular  to  the  surface  separating  the 
  two  media  traversed  by  the  ray. 
  {Conical  refraction}  (Opt.),  the  refraction  of  a  ray  of  light 
  into  an  infinite  number  of  rays,  forming  a  hollow  cone. 
  This  occurs  when  a  ray  of  light  is  passed  through  crystals 
  of  some  substances,  under  certain  circumstances.  Conical 
  refraction  is  of  two  kinds;  external  conical  refraction, 
  in  which  the  ray  issues  from  the  crystal  in  the  form  of  a 
  cone,  the  vertex  of  which  is  at  the  point  of  emergence; 
  and  internal  conical  refraction,  in  which  the  ray  is 
  changed  into  the  form  of  a  cone  on  entering  the  crystal, 
  from  which  it  issues  in  the  form  of  a  hollow  cylinder. 
  This  singular  phenomenon  was  first  discovered  by  Sir  W.  R. 
  Hamilton  by  mathematical  reasoning  alone,  unaided  by 
  {Differential  refraction}  (Astron.),  the  change  of  the 
  apparent  place  of  one  object  relative  to  a  second  object 
  near  it  due  to  refraction;  also  the  correction  required 
  to  be  made  to  the  observed  relative  places  of  the  two 
  {Double  refraction}  (Opt.),  the  refraction  of  light  in  two 
  directions,  which  produces  two  distinct  images.  The  power 
  of  double  refraction  is  possessed  by  all  crystals  except 
  those  of  the  isometric  system.  A  uniaxial  crystal  is  said 
  to  be  optically  positive  (like  quartz),  or  optically 
  negative  (like  calcite),  or  to  have  positive,  or  negative, 
  double  refraction,  according  as  the  optic  axis  is  the  axis 
  of  least  or  greatest  elasticity  for  light;  a  biaxial 
  crystal  is  similarly  designated  when  the  same  relation 
  holds  for  the  acute  bisectrix. 
  {Index  of  refraction}.  See  under  {Index}. 
  {Refraction  circle}  (Opt.),  an  instrument  provided  with  a 
  graduated  circle  for  the  measurement  of  refraction. 
  {Refraction  of  latitude},  {longitude},  {declination},  {right 
  ascension},  etc.,  the  change  in  the  apparent  latitude, 
  longitude,  etc.,  of  a  heavenly  body,  due  to  the  effect  of 
  atmospheric  refraction. 
  {Terrestrial  refraction},  the  change  in  the  apparent  altitude 
  of  a  distant  point  on  or  near  the  earth's  surface,  as  the 
  top  of  a  mountain,  arising  from  the  passage  of  light  from 
  it  to  the  eye  through  atmospheric  strata  of  varying 
  From  Webster's  Revised  Unabridged  Dictionary  (1913)  [web1913]: 
  Angle  \An"gle\  ([a^][ng]"g'l),  n.  [F.  angle,  L.  angulus  angle, 
  corner;  akin  to  uncus  hook,  Gr  'agky`los  bent,  crooked, 
  angular,  'a`gkos  a  bend  or  hollow,  AS  angel  hook,  fish-hook, 
  G.  angel,  and  F.  anchor.] 
  1.  The  inclosed  space  near  the  point  where  two  lines  meet  a 
  corner;  a  nook. 
  Into  the  utmost  angle  of  the  world.  --Spenser. 
  To  search  the  tenderest  angles  of  the  heart. 
  2.  (Geom.) 
  a  The  figure  made  by  two  lines  which  meet 
  b  The  difference  of  direction  of  two  lines.  In  the  lines 
  meet  the  point  of  meeting  is  the  vertex  of  the  angle. 
  3.  A  projecting  or  sharp  corner;  an  angular  fragment. 
  Though  but  an  angle  reached  him  of  the  stone. 
  4.  (Astrol.)  A  name  given  to  four  of  the  twelve  astrological 
  ``houses.''  [Obs.]  --Chaucer. 
  5.  [AS.  angel.]  A  fishhook;  tackle  for  catching  fish, 
  consisting  of  a  line  hook,  and  bait,  with  or  without  a 
  Give  me  mine  angle:  we  'll  to  the  river  there 
  A  fisher  next  his  trembling  angle  bears.  --Pope. 
  {Acute  angle},  one  less  than  a  right  angle,  or  less  than 
  {Adjacent}  or  {Contiguous  angles},  such  as  have  one  leg 
  common  to  both  angles. 
  {Alternate  angles}.  See  {Alternate}. 
  {Angle  bar}. 
  a  (Carp.)  An  upright  bar  at  the  angle  where  two  faces  of 
  a  polygonal  or  bay  window  meet  --Knight. 
  b  (Mach.)  Same  as  {Angle  iron}. 
  {Angle  bead}  (Arch.),  a  bead  worked  on  or  fixed  to  the  angle 
  of  any  architectural  work  esp.  for  protecting  an  angle  of 
  a  wall. 
  {Angle  brace},  {Angle  tie}  (Carp.),  a  brace  across  an 
  interior  angle  of  a  wooden  frame,  forming  the  hypothenuse 
  and  securing  the  two  side  pieces  together.  --Knight. 
  {Angle  iron}  (Mach.),  a  rolled  bar  or  plate  of  iron  having 
  one  or  more  angles,  used  for  forming  the  corners,  or 
  connecting  or  sustaining  the  sides  of  an  iron  structure  to 
  which  it  is  riveted. 
  {Angle  leaf}  (Arch.),  a  detail  in  the  form  of  a  leaf,  more  or 
  less  conventionalized,  used  to  decorate  and  sometimes  to 
  strengthen  an  angle. 
  {Angle  meter},  an  instrument  for  measuring  angles,  esp.  for 
  ascertaining  the  dip  of  strata. 
  {Angle  shaft}  (Arch.),  an  enriched  angle  bead,  often  having  a 
  capital  or  base,  or  both 
  {Curvilineal  angle},  one  formed  by  two  curved  lines. 
  {External  angles},  angles  formed  by  the  sides  of  any 
  right-lined  figure,  when  the  sides  are  produced  or 
  {Facial  angle}.  See  under  {Facial}. 
  {Internal  angles},  those  which  are  within  any  right-lined 
  {Mixtilineal  angle},  one  formed  by  a  right  line  with  a  curved 
  {Oblique  angle},  one  acute  or  obtuse,  in  opposition  to  a 
  right  angle. 
  {Obtuse  angle},  one  greater  than  a  right  angle,  or  more  than 
  {Optic  angle}.  See  under  {Optic}. 
  {Rectilineal}  or  {Right-lined  angle},  one  formed  by  two  right 
  {Right  angle},  one  formed  by  a  right  line  falling  on  another 
  perpendicularly,  or  an  angle  of  90[deg]  (measured  by  a 
  quarter  circle). 
  {Solid  angle},  the  figure  formed  by  the  meeting  of  three  or 
  more  plane  angles  at  one  point. 
  {Spherical  angle},  one  made  by  the  meeting  of  two  arcs  of 
  great  circles,  which  mutually  cut  one  another  on  the 
  surface  of  a  globe  or  sphere. 
  {Visual  angle},  the  angle  formed  by  two  rays  of  light,  or  two 
  straight  lines  drawn  from  the  extreme  points  of  an  object 
  to  the  center  of  the  eye. 
  {For  Angles  of  commutation},  {draught},  {incidence}, 
  {reflection},  {refraction},  {position},  {repose},  {fraction}, 
  see  {Commutation},  {Draught},  {Incidence},  {Reflection}, 
  {Refraction},  etc 
  From  WordNet  r  1.6  [wn]: 
  n  1:  the  change  in  direction  of  a  propagating  wave  (light  or 
  sound)  when  passing  from  one  medium  to  another 
  2:  the  amount  by  which  a  propagating  wave  is  bent  [syn:  {deflection}, 

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