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How is LIGHT Produced?. What is Light?. a wave of energy energy with different wavelengths have different colours part of the electromagnetic spectrum can be artificial or natural. Electromagnetic Spectrum. Luminous: objects that emit their own light i.e. the sun, a flashlight turned on
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What is Light? • a wave of energy • energy with different wavelengths have different colours • part of the electromagnetic spectrum • can be artificial or natural
Luminous: objects that emit their own light i.e. the sun, a flashlight turned on • Nonluminous: objects that do not emit light i.e a flashlight switched off
Light from Incandescence: the process of emitting light because of being heat/high temperature i.e. incandescent light bulb or fire • electricity moves through the filament in the bulb, making it heat up and glow.
Light from Fluorescence: The process of emitting light due to receiving UV or electrical energyi.e. fluorescent lights, neon signs and phosphorescent things.
Light from Phosphorescence:A type of fluorescence. It is specifically when an object emits light after a UV light has been shined on it. • i.e. the hands and numbers of a watch, some glow in the dark toys
Light from Electrical Discharge: The process of emitting light because electricity is passing through a gas i.e. lightning, neon signs + some street lamps.
Fluorescent Lamps Neon Lights Are gas discharge lamps that contain gases, such as neon, that release coloredvisible light when stimulated by electrons. Many street lights use this, with different sorts of gases. • Are just one lighting application of a gas discharge tube. Black lights are essentially fluorescent lamps without a phosphor coating. They mostly emit ultraviolet light, which causes phosphors outside of the lamp (or lining the bulb) to emit visible light .
Light from Chemiluminescence: the process of changing chemical energy into light energy with little change in temperature i.e. glow sticks • Biting into a Winteogreen lifesaver in a dark closet produces sparks!
Light from Bioluminescence: a chemical reaction that takes place inside a living organism that makes them emit light i.e. bacteria, fungi, fireflies etc • Almost 70% of deep-sea fish are bioluminescent!
Demonstration Time We will now look at: • Movies of deep sea creatures that emit light. • We will also look at many things that are fluorescent e.g. “emit light after receiving energy from somewhere else.” • Finally we will demonstrate chemical production of light.
