d) Double slit experiment

f) Young double-slit experiment using visible light 

gi) λ = ax / D = for all waves where a ≪ D 

the experiment

• light → passed through a colour filter

  • to make it monochromatic

• then → diffracted through a single slit

• then → diffracted through double slits

  • exits in phase

  • interfere coherently

• on the screen → bright and dark fringes

  • bright fringes = areas of constructive interference

  • dark fringes = areas of destructive interference

as long as a ≪ D

λ = ax / D

• wavelength of light (m) = distance between the double slits (m) x distance between two bright fringes (m) / distance from the screen to the double slits (m)