Production of Light. Production of Light. Objects can either be: Luminous (produce their own light) ex: Sun Non-luminous can be seen because it is able to reflect light Q: So what are the sources for luminous objects? A: 8 different luminous sources. 1. Light from Incandescence.
Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.
Objects can either be:
Q: So what are the sources for luminous objects?
A: 8 different luminous sources
Incandescence – light produced due to high temperature.
Ex #1: Regular light bulbs (Thomas Edison)
Electricity passes through tungsten wire becomes very hot and emitted light:
~90% released as Infrared light (not visible to naked eye, but we feel the heat)
~10% released as visible light
Ex #2: Metal heated up
Electric Discharge – the process of producing light by passing an electric current through a gas.
Ex #1: Lightning
Electricity passing through air (mixture of gases)
Ex #2: Neon signs
Electricity passing through different gases & producing different colours.
Phosphorescence– the process of producing light by absorption of UV light by special materials (called phosphors) resulting in emission of visible light over a period of time
“Glow in the dark” items
Fluorescence – the immediate emission of visible light as a result of absorption of UV light.
Ex #1: Fluorescent dye in detergent
Ex #2: Fluorescent light
Electric current applied mercury atoms emit UV light UV light strikes fluorescent coating Visible light given off
What does the name suggests?
Chemiluminescence is the production of light as a result of chemical reaction, with little or no heat produced.
Example: Glow stick
Breaking the glass chamber in the stick mixing of chemicals in the stick light produced
The production of light in living organisms as a result of chemical reaction, with little or no heat produced.
Example: Dinoflagellate is a marine plankton that will glow in presence of danger/predator.
The production of light when certain crystals are scratched, crushed or rubbed.
Example: striking 2 sugar cubes against each other.
LED (Light-Emitting Diode): an electronic device that allows an electrical current to flow in only one direction.
Need special materials called semiconductors.
Differences from incandescent bulb:
Example: Christmas lights
LASER: Light Amplification by Stimulated Emission of Radiation
Laser’s unique properties makes it useful in measuring large distances, such as the distance from moon to earth.
Q: How do they do it?
Apollo 11, 14 and 15 mission left corner-cube reflectors on the moon.
Distance calculated as 385,000 km (with an accuracy of 3 cm)