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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: