• The Rayleigh Criterion can be mathematically described by considering?angular separation?and?single-slit diffraction
• Angular separation can be calculated using the equation:

• 
• ?Where:
  • θ?= angular separation (rad)
  • s?= distance between the two sources (m)
  • d?= distance between the sources and the observer (m)

Angular separation, θ, is equal to the separation, s, of two sources?divided by the distance, d, between the sources?and the observer

• In single slit diffraction, the first minimum occurs when the angle of diffraction is:

• • Wavelength of light sources, λ = 530 nm = 530 × 10?9?m
  • Student pupil diameter,?b?= 6.0 mm = 6.0 × 10?3?m
  • Distance from the helicopter light sources to the student's eye,?d?= 6.0 km = 6 × 103?m

• • Since the lights can just be resolved, this is Rayleigh's criterion
  • The equation needed is:

• • The approximate distance between the light sources on the helicopter,?s?=?65 cm

• • Wavelength of light sources, λ = 500 nm = 500 × 10-9?m
  • Student pupil diameter,?b?= 4.0 mm = 4.0 × 10-3?m
  • Distance of separation between headlights,?s?= 1.5 m

• • Since the answer will occur when Rayleigh’s criterion is met, the equation needed is: