Light

Light

1. Reflecting light

   • Law of reflection
     • Angle of incidence=Angle of reflection
     • Incident ray , refracted ray and normal lie on the same plane

2. Image in a plane mirror

   • Result of reflection of light
   • Plane mirror: image with flat surface
   • It is Virtual Image

3. Ray Diagram ( Image formed characteristics )

   • Same size as object
   • The distance behind the mirror , same as distance infronte of mirror
   • Laterally inverted
   • Virtual

4. Light refraction

   • Bending of rays
   • Speed changes
   • Direction changes
   • Law of refraction
     • Sine i directly proportional to sine r
     • Incident ray ,refracted and normal lie on the same plane
   • Parallel sided block
   • Refractive index
     • Describe how ray of light slow down when enter new medium
     • No unit
     • Represented by (n)
     • n=c\v
     • speed of light in vacuum =3*10^8
       • Represented by (c)
     • The denser the medium the higher the refractive index
     • Snell`s law
       • Relates angle (i) and (r)
       • from air to another medium
         • n=sin i\sin r
       • from denser medium to air
         • n=sin r\sin i

5. Semi circular glass

   • critical angle
     • light travel from denser to rarer
     • i=c
     • r=90
   • Total internal reflection
     • Angle (i) greater than (c)
     • Light travel from denser to rarer
     • Total ,light 100% reflected
     • Total, happen inside the glass
     • Reflection,all light reflected

6. Critical angle and refractive index

   • The greater the refractive index the smaller the critical angle
   • Relating formula
     • n=sin90\sinc

7. Optical fibers

   • glass fibers
   • based on total internal reflection
   • Application
     • Telecommunication
     • In medicine (endoscope)

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