Light

• laws of reflection

  • angle of incidence is equal to angle of reflection
  • incident ray, normal and reflected ray lie on the same plane
• plane mirror

  • virtual and erect
  • equal size
  • equal distance
  • laterally inverted
• concave, beyond C

  • real, inverted
  • diminished
  • between C and F
• concave, at infinity

  • real, inverted
  • highly diminished
  • at F/focus
• concave, at C

  • real, inverted
  • same size
  • at C
• concave, between C and F

  • real, inverted
  • enlarged
  • beyond C
• concave, at F

  • real, inverted
  • highly enlarged
  • at infinity
• concave, between F and P

  • virtual, erect
  • enlarged
  • behind mirror
• convex, between infinity and pole

  • behind mirror between F and P
  • virtual, erect
  • diminished
• convex, at infinity

  • behind mirror at F
  • virtual, erect
  • point sized
• uses of concave mirror

  • torches
  • headlights
  • shaving mirror
  • dentist
  • solar furnace
• uses of convex mirror

  • rear view mirror
• refractive index: the ratio of speed of light in vacuum to speed of light in medium
• larger the refractive index the more it bends
• laws of refraction

  • incident ray, refracted ray and normal all on same plane
  • ratio of sin of angle of incidence to the sin of angle of refraction is constant
• Sell's law: ratio of sin of angle of incidence to the sin of angle of refraction is constant
• power of lens is defined as the inverse of its focal length
• convex lenses are converging so they have positive power
• concave lenses diverge so they have negative power
• the more the curvature of the surface the higher the power
• thicker lenses have lower powers than thinner ones