What Is Light? Optics is the study of light Light Is a form of energy Travels in straight lines Is...
-
Upload
rafe-walsh -
Category
Documents
-
view
217 -
download
1
Transcript of What Is Light? Optics is the study of light Light Is a form of energy Travels in straight lines Is...
What Is Light?
Optics is the study of light
Light • Is a form of energy• Travels in straight lines• Is transferred by radiation• Is an electromagnetic wave
The Electromagnetic Spectrum
The Electromagnetic Spectrum
Electromagnetic Wave: A wave that has both electric and magnetic parts, is radiated and travels at the speed of light
Electromagnetic Spectrum: The classification of electromagnetic waves by energy
• Electromagnetic waves that the human eye can detect
• White light is composed of a spectrum of colours (ROYGBIV)
Interactions of Light with Matter
Types of Materials:• Transparent: light passes through
– e.g. water, glass
• Translucent: light is scattered– e.g. frosted glass, stained glass
• Opaque: no transmission of light – e.g. stone, wood
Light Can Be:Transmitted (passes through) Reflected (change direction)Absorbed (stopped from passing through)
Properties of Light
1. Light always travels in straight lines
2. Light is invisible until reflected by translucent or opaque objects
3. Light can be transmitted, reflected or absorbed by different types of materials
How is Light Produced
Luminous: Produces its own light (e.g. the sun, stars, a light bulb, a fire)
Non-Luminous: Does not produce its own light. Only visible when illuminated by a luminous source (e.g. the moon, a tree, a book, humans)
Most objects are non-luminous.However, there are many luminous
sources…
Luminous Sources
INCANDESCENCE: • The production of light as a
result of high temperature• Examples:
Luminous Sources
ELECTRIC DISCHARGE: • The process of producing light
by passing an electric current through a gas
• Examples:
Luminous SourcesPHOSPHORESCENCE: • The process of producing light by
the absorption of ultraviolet light resulting in the emission of visible light over an extended period of time
• Examples:
Luminous SourcesFLUORESCENCE: • The immediate emission of
visible light as a result of the absorption of ultraviolet light
• Examples:
Luminous SourcesCHEMILUMINESCENCE: • The direct production of light as
the result of a chemical reaction with little or no heat produced
• Examples:
Luminous SourcesBIOLUMINESCENCE: • The production of light in living
organisms as the result of a chemical reaction with little or no heat produced
• Examples:
Luminous Sources
TRIBOLUMINESCENCE :• The production of light
from friction as a result of scratching, crushing, or rubbing certain crystals
Luminous Sources
LIGHT EMITTING DIODE (LED):• Light produced as a result of an
electric current flowing in semiconductors
• Examples: