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Chapter 5 Optics (5.1 (Glass to air vs air to glass (i1 and r1= angles of…

- - - - Incident substance has larger refractive index than other substance
      - Angle of incidence exceeds critical angle
- - - - Lamp- Double slit creates two coherent (emit waves with constant phase difference and same freq..)light sources
      - Creates alternate bright and dark fringes known as Young's fringes
      - Fringes evenly spaced and parallel to slits
      - Can use a laser- must be displayed on screen as laser can damage retina
      - Bright fringe- light from one slit reinforces light from the other
      - Dark fringe- light from one slit cancels the other- antiphase
- - - - Use ripple tank to observe
      - Waves spread out more if
        
        Gaps narrower
        
        Wavelength is larger
    - - Direct a parallel beam of light at the slit
      - Forms pattern that you observe on a white screen
      - Central fringe has greatest intensity and has 2x the width
      - Peak intensity decreases as you move away from centre
      - Greater wavelength= wider fringe
      - Narrower slit= wider fringe
- - - - Light passing through each slit's diffracted
      - Diffracted light waves from adjacent slits reinforce in certain directions only
    - - Continuous- Continuous spectrum of light- most intense part depends on temperature of light source, higher temp. shorter wavelength- measure wavelength of brightest part you can calc. temp. of source
      - Line emission- Glowing gas in a vapour lamp or discharge tube emits light at specific wavelengths= narrow lines of different colours
      - Line absorption- Continuous spectrum with narrow dark lines at certain wavelengths. This is due to elements in the glowing gas that absorbs light of the wavelengths they emit so transmitted light is missing this wavelength
- - - - Differs from normal light
        
        Mainly monochromatic- can specify wavelength to within a nm
        
        Coherent light source- electrons emit a photon which emits photon that are in phase with the one that emitted it
  - - - Inner fringes tinged with blue outer fringes tinged with red- more/less spaced out
      - Central fringe pattern white as all colours contribute to it
      - Outer fringes merge into an indistinct background of white light becoming fainter because as fringes different colours reinforce and overlap