1 / 42

How We See

How We See. Ms. Kueh Wednesday, April 23, 2014. UNDERSTANDING SIGHT. To understand sight, you have to understand: Light Eye-Brain combination We will focus mostly on how light behaves in the physical world. The study of this is called Optics. Spiral.

awildad
Download Presentation

How We See

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. How We See Ms. Kueh Wednesday, April 23, 2014

  2. UNDERSTANDING SIGHT • To understand sight, you have to understand: • Light • Eye-Brain combination • We will focus mostly on how light behaves in the physical world. • The study of this is called Optics

  3. Spiral • http://www.michaelbach.de/ot/mot_adaptSpiral/index.html

  4. EYE & BRAIN • We see things using a combination of our eyes and brain. http://www.michaelbach.de/ot/mot_adaptSpiral/index.html

  5. Optical Illusions • Upside Down Goggles • http://www.ted.com/talks/beau_lotto_optical_illusions_show_how_we_see

  6. SAY HELLO TO EYEVAN! • Eyevan the Eye-Brain will be used throughout our lessons, so get used to seeing him!

  7. LET’S PLAY WITH LASERS! • Why can’t we see a laser until it hits the wall or another object?

  8. SEE IT TO BELIEVE IT • Tyndall Effect describes the reflection of light by very small particles in suspension in a transparent (See-through) medium

  9. ANOTHER WAY TO THINK OF LIGHT • Light leaving the candle travels in all directions, but we only SEE the light that travels in to our Eye-Brain

  10. ANOTHER WAY TO THINK OF LIGHT (CONT’D) • We don’t see light that doesn’t enter our eyes.

  11. ANOTHER WAY TO THINK OF LIGHT (CONT’D) • If the light going away from eyes is reflected in to our Eye-Brain, then we will see it.

  12. SIDE NOTE • When we look at diagrams, we will ignore light that doesn’t enter our Eye-Brain. • Don’t forget that the other light exists, we are just ignoring it to simplify our lives!

  13. RAYS & DIAGRAMS • Ray Diagrams show how light moves from the object to the eye. • Light Ray – a line on a diagram representing the direction and path that light is travelling.

  14. RAYS & DIAGRAMS • Lightis a type of energy our eyes are sensitive to. • Considered an Operational Definition because it only describes HOW we detect light, but doesn’t tell us WHAT light is.

  15. RAYS & DIAGRAMS • Rectilinear Propogation describes how light always travels in straight lines. • Think of shadows and what they look like. They perfectly copy whatever the object is.

  16. CAN HESEE EYEVAN’S FEET? • Based on what you know so far about light rays and how you see, would you be able to see Eyevan’s feet?

  17. CAN YOU SEE EYEVAN’S FEET? • Light travels in straight lines from Eyevan’s feet, but not directly in to your eyes. (Rectilinear Propagation)

  18. WHAT YOU SEE

  19. Colours

  20. Additive Colour Theory of Light • white light is composed of  different colours (wavelengths) of light • white light can be produced combining only three colours • One such combination is red, green and blue

  21. Additive Colour Theory of Light • Primary Colours for Light • Red, Green, Blue • If you mix only two primary colours together you make a secondary colour.

  22. When Light Hits an Object • It can be absorbed • It can bounce off the object (reflect) • It can change direction (refraction in transparent objects)

  23. Subtractive Colour Theory of Light • The colour you see when you look at an object depends on the wavelengths that are reflected

  24. How do we get the colour black?

  25. How do we get the colour black? •  A black object absorbs all colours while a white object  reflects all colours. A blue object reflects blue and absorbs all other colours.

  26. Subtractive Colour Theory of Light •  The primary and secondary colours of light for the subtractive theory are  opposite to the colours of the additive theory.

  27. Subtractive Colour Theory of Light •  Cyan, magenta and yellow are the primary subtractive colours  while red, green and blue are the secondary subtractive  colours.

  28. LUMINOUS SOURCES • Atoms in LUMINOUS OBJECTS emit light rays in all directions produced from other energy sources. • Atoms in NON-LUMINOUS OBJECTS scatter the light rays from luminous objects in all directions.

  29. NOTE • Atoms in all objects produce or scatter light rays. This diagram only shows light rays from atoms at the top and bottom of the objects.

  30. KEEP IT SIMPLE • To make diagrams simpler, we only show one ray of light from the top and bottom of objects. • We simplify it even more and just show only the rays coming from the top of the object.

  31. MEDIUMS • A TRANSPARENT MEDIUM allows nearly all rays to pass straight through unaltered. (Ex. Air) • An OPAQUE MEDIUM absorbs or scatters all the rays. (Ex. Textbook, wall, etc.)

  32. MEDIUMS (CONT’D) • A TRANSLUCENT MEDIUM transmits and scatters the rays. The medium indicates whether it is being illuminated by the object can not be clearly seen. (Ex. Wax Paper)

  33. Depth Perception Depth Perception - Two eyes in front of a head can determine the object’s location better because the rays entering each eye can be used by brain to triangulate where the object is.

  34. Depth Perception Pencil Touch Activity!

  35. The Floating Finger • Hold your left and right forefingers about 30 cm in front of your eyes. Hold them horizontally about 2-3 cm apart. • Focus your eyes at a far point. Do not focus on your fingers.

  36. The Floating Finger Did you see a piece of finger floating in the air?

  37. The Floating Finger The eyes are focused on a point located far away. The Eye-Brain uses two slightly different sets of rays to triangulate the distance. But we still see objects that are closer to the eyes.

  38. Right Eye Image Left Eye Image Both Eye Images Combined

  39. EXAMPLE OF CONFUSION • Animals with eyes on the side of their head (like horses) can only see the object with one eye at a time. • They can not use the triangulation method to determine the object’s location.

  40. Horse’s Eye-sight • These animals must use the object’s apparent size to determine its location. • Their depth perception will be poor.

  41. Magic Eye and Depth Perception

  42. HOMEWORK • Read section 11.4 • Homework: pg. 481 #1, 3, 5 (draw a diagram)

More Related