Chapter 15 AVisible Light and Its Sources Visible
Chapter 15 AVisible Light and Its Sources
Visible Spectrum • 780 nm (Dark Red) – 380 nm (dark purple) • 384 THz – 789 THz • Each person sees colors a little different
Visible Spectrum • All light possible: visible spectrum • Created by luminous objects
Visible Spectrum • Luminous objects- create light • Only 1 color: monochromatic • Example: LEDs (light-emitting diodes) • Illuminated objects- reflect light
Visible Spectrum
Visible Spectrum • Continuous Spectrum • All possible wavelengths of visible light • Line Spectrum • Distinct visible lines of color • Shows what exact wavelengths a gas does not absorb • Spectrograph • Photograph, printout, or display of a spectrum made by a spectroscope (something that breaks up light into the colors it is made of)
Visible Spectrum
Visible Spectrum
Speed of Light • 299792458 m/s • 3. 0 x 108 m/s • Light minute • Distance light travels in 1 minute • Sun is 8. 3 light minutes away • Light year (ly) • • • Distance light travels in 1 year 9. 5 trillion km!!! Nearest 3 stars are 4. 4 ly away
Intensity of Light • Illumination- amount of light you receive • How does it relate as you move from the source? • Inverse square law
Types of Light • Incandescence • Made by hot, glowing material
Types of Light • Fluorescence • Visible light is radiated when it absorbs higher energy
Types of Light • Phosphorescence • Glow-in-the-dark! • Light caused by absorbing energy and releasing it as light
Types of Light • Monochromatic light • Made by coherent light • All photons have the same wavelength (same color)
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