Paper 3 - Option Module - Turning Points - 3.12.2 - Wave-Particle duality Flashcards
3.12.2.1 Newton’s corpuscular theory of light
3.12.2 Wave-Particle duality
What did Newton imagine a light ray as?
A stream of particles called corpuscles.
What are corpuscles?
Tiny particles of negligible mass.
What are the corpuscles assumed to be, in terms of their motion?
Perfectly elastic.
Draw the diagram of how newton’s corpuscular theory explained refraction?
In page 9.
What happened to corpuscles as they entered a more dense medium (explanation of refraction)?
Corpuscles are attracted into the substance of the more dense medium.
Perpendicular component of velocity increases, but parallel component remains constant.
Corpuscles/light speeds up in more dense medium.
What was Huygen’s theory?
Wave theory of light.
How did Huygen explain refraction?
Light waves travel slower in more dense substances.
Why was Newton’s theory preferred over Huygen’s?
Newton had a stronger reputation than Huygen.
Wave theory was in terms of longitudinal waves and couldnt explain polarisation.
3.12.2.2 - Significance of Young’s double slit experiments
Draw a diagram of the observations and set-up of the Young’s double slit experiment.
Page 10.
Explain, using waves, bright fringe formation.
Light waves from each slit arrive in phase, so they constructively reinforce each other. Path difference between the waves is a whole number integer of wavelengths.
Explain, using waves, dark fringe formation.
Light waves from each slit arrive 180 degrees or Pi radians out of phase, so undergo destructive interference. Path difference between the waves is a odd number of half a wavelength.
What does the fringe spacing (w) depend on?
Slit spacing.
