2. 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

3. The Electromagnetic Spectrum

4. 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

5. Electromagnetic waves that the human eye can detect White light is composed of a spectrum of colours (ROYGBIV)

6. 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

7. Light Can Be: Transmitted (passes through) Reflected (change direction) Absorbed (stopped from passing through)

8. 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

9. 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…

10. Luminous Sources INCANDESCENCE: The production of light as a result of high temperature Examples:

11. Luminous Sources ELECTRIC DISCHARGE: The process of producing light by passing an electric current through a gas Examples:

12. Luminous Sources PHOSPHORESCENCE: 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:

13. Luminous Sources FLUORESCENCE: The immediate emission of visible light as a result of the absorption of ultraviolet light Examples:

14. Luminous Sources CHEMILUMINESCENCE: The direct production of light as the result of a chemical reaction with little or no heat produced Examples:

15. Luminous Sources BIOLUMINESCENCE: The production of light in living organisms as the result of a chemical reaction with little or no heat produced Examples:

16. Luminous Sources TRIBOLUMINESCENCE : The production of light from friction as a result of scratching, crushing, or rubbing certain crystals

17. Luminous Sources LIGHT EMITTING DIODE (LED): Light produced as a result of an electric current flowing in semiconductors Examples: