THE NATURE OF LIGHT
THE NATURE OF LIGHT
LIGHT BEHAVIOR• Light behaves like a wave and like a particle.
WAVE NATURE OF LIGHT
•Electromagnetic radiation is a form of energy that exhibits wavelike behavior as it travels through space.• 7 different types:
WAVE CHARACTERISTICS•Wavelength – distance between 2 crests or 2 troughs• Symbol: λ (lambda) Units: m, nm
• Frequency – number of waves that pass a point per second
• Symbol: ν (nu) Units: hertz (Hz), s-1
•Amplitude – wave’s height from origin to crest or trough
WAVE CHARACTERISTICSLABEL: ORIGIN, CREST, TROUGH, WAVELENGTH AND AMPLITUDE
WAVE TRAVEL• All electromagnetic waves, including visible light, travel
at the speed of light (c) in a vacuum.
c = 3.00 x 108 m/s
• Although the speed of all EM waves is the same, waves have different wavelengths and frequencies• Formula: c = λν
• Relationship:
WAVE TRAVELIDENTIFY AND LABEL: LOW/HIGH FREQUENCY, LONG/SHORT
WAVELENGTH AND LOW/HIGH ENERGY
WHITE LIGHT• When white light is passed
through a prism, it is separated into a spectrum
• 7 colors
• It is continuous because there is NO portion of it that does not correspond to a unique frequency and wavelength of light
ELECTROMAGNETIC SPECTRUM
PARTICLE NATURE OF LIGHT
• The Quantum Concept: When objects are heated, they can glow different colors at different temperatures. This is because they are emitting different frequencies of light
MAX PLANCK (1900)• Concluded that matter can
gain or lose energy only in small, specific amounts called quanta• Proposed that the light
being emitted was quantized
• Quantum – minimum amount of energy that can be gained or lost by an atom
MAX PLANCK (1900)
• Demonstrated mathematically that the energy of a quantum is related to the frequency of the emitted radiation by Planck’s constant (h)
h = 6.63 x 10-34 J/Hz• Formula: E = hν
• Relationship: