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: