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Light and Optics. Properties of Light. Light… …travels in straight lines …travels at a speed of 300,000 km/sec (8 trips around the world in 1 second!) …travels faster than sound Thunder and Lightning Pistol fired …from the Sun is converted to heat when it reaches the earth
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Properties of Light Light… …travels in straight lines …travels at a speed of 300,000 km/sec (8 trips around the world in 1 second!) …travels faster than sound Thunder and Lightning Pistol fired …from the Sun is converted to heat when it reaches the earth Is absorbed, reflected or passes through an object Vision as a reflection of Light Shadows Luminous vs non-luminous objects
Luminous vs non-luminous A luminousobject is one that produces light Examples: • Sun • Light Bulb • Electrical Discharge A non-luminousobject is one that reflects light Examples: • Moon • Tree • Clouds
Light Energy… Light allows us to visually observe the world around us by illuminating dark spaces Producing light by IncandescencevsLuminescence Incandescence Light given off by an object as a result of the heat produced in a chemical reaction Luminescence Light given off by an object that has not been heated. Observed as fluorescence, electrical discharge or chemiluminescence
Light and Energy… Examples of light-producing technologies from luminescence
Electromagnetic Waves Light is energy and travels like a wave Energy we call light is related to certain other forms of energy. You may have heard of microwaves, ultraviolet or UV rays, Xray. Eachof these forms of energy are generally grouped as Electromagnetic waves The electromagnetic spectrum is the entire range of electromagnetic waves arranged according to their frequencies or wavelengths Electromagnetic waves all have different properties. But they all travel the same speed – what we call “The speed of light”
Electromagnetic Spectrum The electromagnetic spectrum represents the range of energy from low energy, low frequency radio waves with long wavelengths up to high energy, high frequency gamma waves with small wavelengths.
Electromagnetic Spectrum 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.