4.1b Types of Light
Groups Neala, Harrison, Adriana Destiny, Abbey, Noah Nico, Emma, Zak Amber, Claire, Cristian Connor, Josh, Brianna Blake, Brett, Aidan, Jazmine
Group Work Group member 1: manager - keep everyone on task making sure everyone stays on topic Group member 2: recorder – make sure every group member has recorded all of the information Group member 3: time tracker - keep an eye on the time
Luminous vs non-luminous Luminous objects create their own light Non-Luminous do NOT create their own light Think of some more in your group
Luminous Sources of Light Natural Sources Produced without human intervention Ex. Sun, fireflies Artificial Sources Produced and controlled by humans Ex. Neon signs, flashlight, TV screen
Incandescence vs Luminescence
Incandescence Light is emitted when a material has been heated Incandescent light bulbs heat a thin wire filament with electricity Ex. burning candle, light bulb, burning fuel
Luminescence Light given off by an object that has not been heated Eg. Glow sticks, fluorescent lights
T-Chart Comparing the Two Forms of Light In your group, think of as many examples of incandescence and luminescence that you can
Electric Discharge Light produced when an electric current passes through a gas (which causes the gas to glow) Eg Neon lights Static electricity is built up between the sky and the ground and then large amounts of electricity travel through the air (gas) and hit the ground. Lighting up the skies
Fluorescence An object absorbs UV light and releases visible light immediately Fluorescent lights: Tube is filled with low pressure mercury vapour and is coated with a fluorescent material mercury atoms emit UV light and transfers it to the fluorescent surface to produce light Use less energy and produce less heat
Chemiluminescence Light produced by a chemical reaction Gives off no heat Ex. glow stick
Bioluminescence When chemiluminescence occurs in living organisms Used by many organisms to protect themselves from predators, to lure prey or attract mates Ex. firefly
Triboluminescence Light produced by friction (scratching, crushing or rubbing) between certain crystals Ex. rubbing two quartz crystals together, wintergreen mints
LED Lights (Light-Emitting Diode) Light produced as a result of an electric current flowing in semiconductors Semiconductor: a material that allows an electric current to flow in only one direction LED’s do not need a filament Does not produce much heat (wasted energy) More energy efficient Used in Christmas lights and traffic lights
Pros and Cons Pick a Form of Light and Brainstorm some pros and cons of using that form of light. Be prepared to present your information Group member 1: manager - keep everyone on task making sure everyone stays on topic Group member 2: recorder - record groups ideas Group member 3: time tracker - keep an eye on the time