NATURE OF LIGHT Flashcards
EARLY EXPERIMENTS
→ the first experiment to find the speed of light was by measuring how fast light could travel between 2 hills, however it was too fast to measure.
SPEED OF LIGHT EXPERIMENTS
→ the fizeau wheel: measured the angular speed of the wheel in rotations per second. Involved light making a round trip to the mirror. Calculated the speed of light as 3.13x10^3 m/s
→ Jean foucault: had a more sophisticated experiment system that used rotating mirrors. Calculated the speed of light as 2.98x10^8
DUAL NATURE OF LIGHT
→ light has characteristics of both particles (isaac newton) and waves (christian huygens)
De broglie wave theory: light propagates like a wave but exchanges energy like a particle.
SPEED OF LIGHT IN OTHER MEDIA
→ the speed of light in the air (3.0x10^8) is similar to the speed of light in a vacuum, however when changing mediums, it slows down. The denser the medium, the larger the refractive index, and the more light slows down.
DIFFRACTION OF LIGHT
→ is the bending of light through or around a barrier
→ when light hits a barrier, it creates an area absent of light thus creating a shadow.
→ when light hits a barrier it reflects back, but the other side of the wave bends behind the barrier
Total internal reflection: occurred when light passes through dense to less dense medium. Also occurred when angle of incidence is greater than the critical angle (90 degrees)
DISPERSION OF LIGHT
→ the spreading of white length into all its different wavelengths (coloured)
→ particles of light are called photons
Photons have no mass but have energy
Move with the speed of light
Are electrically neutral
The longer the wavelength the less energetic the photon, the shorter the wavelength, the more energetic the photon.
CONSTRUCTIVE AND DESTRUCTIVE INTERFERENCE (DOUBLE SLIT EXPERIMENT)
constructive: 2 waves overlap one another to create a larger wave
destructive: 2 waves overlap in a way which makes them cancel out
