Unit 2 - Optics

Chapter 4

Many Properties Of Light Can Be Understood Using A Wave Model Of Light

The Nature of LightInvestigation of Light History

4.1. page 132.

What are these dates important and who are these scientists?

• 580 BCE - Pythagoras• 965 CE - Ibn al-Haytham• 1200 - Reading stones… spectacles• 1500 - Zaccharias and Hans Janssen• - Anton van Leewenhoek• 1638 - Galileo Galilei• 1800 - Thomas Young and Augustin Frensil• - Albert Mendelson

Inventions Related to Light

• Reading stone

• Spectacles

• Microscope

• Telescope

• Laser eye treatment

• Bioluminescent night lights

Two Misconceptions of Light4.1: page 132-137

1.) Light is a straight beam that travels in a straight line.Wrong!

Light is energy waves that travels in a straight line.

2.) Light is made up of Particles.Wrong!

Light is energy

3.) The eye sends out fibers which touches an object, gathering information from it. Wrong!The eye receives light wave.

Properties of of Waves4.2: Pages 138-147

• Crest, Trough, Wavelength, Amplitude, Rest Position and Frequency.

• Frequency is measured in Hertz (Hz).

• A wavelength can be describe in meters, Amplitude and Frequency.

Types of Waves

• Transverse Waves

• Compression Waves

Transverse Waves

• A Transverse wave travels in an up and down motion through a medium.

Compression Waves

• A compression wave travels back and forth through a medium.

Assigned Class Work

• Page 142

• Questions 1-5

Optical Mind Tricks

• http://www.eyetricks.com/illusions.htm

Expansion optical illusion with bubble – Demonstrate.

Properties of Visible Light4.3: 148-144

Light Waves

• Visible light is wave that you can see with the human eye. Many other light waves exist that humans can not see.

White vs. Black

• White is total colour.

• Darkness in the absence of colour.

The Electromagnetic Spectrum4.4 page 156

• The electromagnetic spectrum includes all the visible and invisible waves of light.

Wavelength MeasurementThe Visible Light Spectrum

• Wavelengths of light are measured in nanometers (nm)

Another Diagram …

Visible LightThe Spectrum of White Light

Waves Unable to be Seen

Wavelengths Longer than Visible Light• Radio Waves• Mircowaves• Infrared waves

Light Waves Shorter than Visible Light• Ultraviolet• X Rays• Gamma Rays

Reflection vs. RefractionPage 149 and 152

• Reflection occurs when light waves strikes an object and bounces off.

Rectilinear Propagation“Shadows”

• Refraction is the bending or changing of

direction of a wave as it passes through one material to another.

Chapter FiveThe Law of Reflection Allows Mirrors to

form Images

Plane Mirrors

Concave Mirrors

Convex mirrors* Mirrors differ in shape and location of focal point. These

feature produce varying images.

Images in Mirrors

Images may vary in:

1.) Size – large or small

2.) Distance – long or short

3.) Orientation - Upright or Inverted

4.) Perspective – Virtual or real

Plane Mirrors

Plane Mirrors - Images

• Image size is equal to object size.

• Image distance is equal to object distance.

• The image is upright.

• The image is virtual.

*** All images are reversed in mirror.

Concave Mirrors

Concave Mirrors - Images

Pending on the location of an object – images will vary:

• Images between the focal point and the mirror.

• Images between the focal point and two times the focal point.

• Images beyond two times the focal point.

Convex Mirrors

Convex Mirrors - Images

• The Image is smaller than the object.

• The image distance is smaller than the object distance.

• The image is inverted.

• The image is real.

Lenses

Two Types of Lenses:

• Concave Lenses

• Convex Lenses

Concave Lenses

• Concave lenses refract light wave out and away from the lens.

• The glass at the middle of the lens is thinner than at its edges.

Convex Lenses

• Convex lenses refract light towards a focal point.

• The glass in the middle of the lens is thicker than its edges.

Just for EnrichmentThe Human Eye