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Electromagnetic Spectrum. Light Phenomenon. Isaac Newton (1642-1727) believed light consisted of particles By 1900 most scientists believed that light behaved as a wave. . The Electromagnetic Spectrum. The electromagnetic spectrum represents the range of energy from low energy to high
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Light Phenomenon • Isaac Newton (1642-1727) believed light consisted of particles • By 1900 most scientists believed that light behaved as a wave.
The Electromagnetic Spectrum The electromagnetic spectrum represents the range of energy from low energy to high Low energy = long wavelengths & low frequency High energy = short wavelengths and high frequency
Visible light is a small portion of this spectrum. This is the only part of this energy range that our eyes can detect. What we see is a rainbow of colors. RedOrangeYellowGreenBlueIndigoViolet ROY G BIV
The visible spectrum falls within the range of the Sun’s electromagnetic energy—our eyes have evolved to take greatest advantage of the available light.
Wavelengths and Frequency Wavelength = the distance between two peaks in a wave Frequency = how often a wave passes (or hits) an object High frequency = short wavelength Low frequency = long wavelength
Particles of light are governed by the Speed of Light Equation C = λν • The frequency (v) of a wave is the number of waves to cross a point in 1 second (units are Hertz – cycles/sec or sec-1) • Megahertz (mHz) = 1,000,000 Hz • Kilohertz (kHz) = 1,000 Hz • λ is the wavelength- the distance from crest to crest on a wave
The product of wavelength and frequency always equals the speed of light. C = λν • Why does this make sense? • NOTE: c is a constant value= 3.00 x 108 m/s
PROBLEMS • Calculate the wavelength of yellow light emitted from a sodium lamp if the frequency is 5.10 x 1014 Hz can be written 5.10 x 1014s-1 1) List the known infoList the unknown c = 3.00 x 108 m/swavelength (λ) = ? cm Frequency (v) = 5.10 x 1014 s-1 2) Rearrange the Equation and plug in the knowns c= λvλ= c v λ = 3.00 x 108 m/s= 5.88 x 10-7 m 5.10 x 1014 s-1