Sources of Light Flashcards
What are luminous objects?
Objects that produce their own light. E.g. The sun
What is light?
A form of energy that is visible (that our human eyes are capable of sending)
What are non-luminous objects?
Objects that do not produce their own light. E.g. The moon (reflects the sun’s light)
What are some examples of natural light?
The sun, lightening, fire.
What are some examples of artificial light?
Lightbulb, iPhone
Materials that give off light must first absorb some sort of what?
Energy
Describe incandescence light
Light is given off a material because it is not very hot. Not very efficient, most of the energy given off is heat and not light (95% heat, 5% light)
Give an example of incandescence light
- hot burner on stove
- incandescent light bulb
- lit match
- gas lantern
Describe electric discharge
Produced by an electrical current passing through a gas (atoms get excited)
Different gases produce different colours (noble gases)
Give an example of electric discharge
- lightening
* neon signs
Describe fluorescence light
Occurs when an object absorbs UV rays and immediately releases the energy as visible light
4x more effective than incandescence light
Give an example of fluorescence light
- highlighters which contain fluorescent dies
- some detergents contain fluorescent dyes to make clothes look brighter
- used in ultra white paper
Describe light-emitting diodes (LED’s)
And electric device that allows electrons to flow in a solid semi-conductor and release light
Non-filament, little heat produced, energy efficient, no mercury, light given off with no heat
Give an example of LED’s
• christmas lights
Describe phosphorescence light
Light is produced after the absorption of UV rays and the energy is stored
Also known as ‘glow in the dark’
