Electromagnetic Spectrum

Light Phenomenon Isaac Newton ( ) 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. R ed O range Y ellow G reen B lue I ndigo V iolet 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.

Sodium Lights

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 10 8 m/s

Calculate the wavelength of yellow light emitted from a sodium lamp if the frequency is 5.10 x Hz can be written 5.10 x s -1 1) List the known infoList the unknown c = 3.00 x 10 8 m/swavelength (λ) = ? cm Frequency (v) = 5.10 x s -1 2) Rearrange the Equation and plug in the knowns c = λv λ = c v λ = 3.00 x 10 8 m/s = 5.88 x m 5.10 x s -1 PROBLEMS