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Unit 2 - Optics
Chapter 4
Many Properties Of Light Can Be
Understood Using A Wave Model Of
Light
The Nature of Light
Investigation of Light History
4.1. page 132.
What are these dates important and who are these
scientists?
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580 BCE
965 CE
1200
1500
1638
1800
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Pythagoras
Ibn al-Haytham
Reading stones… spectacles
Zaccharias and Hans Janssen
Anton van Leewenhoek
Galileo Galilei
Thomas Young and Augustin Frensil
Albert Mendelson
Inventions Related to Light
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Reading stone
Spectacles
Microscope
Telescope
Laser eye treatment
Bioluminescent night lights
Two Misconceptions of Light
4.1: 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 Waves
4.2: 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 Light
4.3: 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 Spectrum
4.4 page 156
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The electromagnetic spectrum includes
all the visible and invisible waves of light.
Wavelength Measurement
The Visible Light Spectrum
• Wavelengths of light are measured in
nanometers (nm)
Another Diagram …
Visible Light
The 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. Refraction
Page 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 Five
The Law of Reflection Allows Mirrors to
form Images
Plane Mirrors
Concave Mirrors
Convex mirrors
* Mirrors differ in shape and location of focal point.
feature produce varying images.
These
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 Enrichment
The Human Eye