1. Optics Test
Study this PowerPoint

2. What is an optical Illusion?
A perceived image that is different from reality. The eye gathers information that the brain tries to understand.

3. How can we view light energy?
Sun
Colour
Mirrors

4. Facts about light
Light didn’t appear until nearly half a million years after the Big Bang
Light moves at 186, 000 miles per second
Light has a hard time moving through a diamond, this is what causes the sparkle
Eyeglasses bend light as it travels from the air to lens, fixing vision problems
Ancient Greeks thought we could see by shooting light from our eyes
People are bioluminescent and are brightest around noon, around the lips and cheeks
90% of all sea creatures below 1500 ft give off light
100 W light bulb can produce 325 F in a confined space
Visible light makes up one ten-billionth of the electromagnetic spectrum
Some animals like bees, birds and lizards can see ultraviolet light

5. Questions: 268-277 What is the most important source of natural light?
What are the 6 sources of light what does each mean?
What happens when light strikes an opaque surface?
What the 3 properties used to describe the amount of light energy absorbed or reflected?
What are the 4 characteristics of an image?

6. Answers: Sun is the most important source of natural light.
When light hits an opaque surface no light can transmit through and all light is either absorbed or reflected.
Colour, sheen [shininess] and texture are the 3 properties that describe the amount of light energy reflected or absorbed.
Four characteristics of an image; size, attitude, location, and type.

7. Answers Six sources of light:
Incandescence-light produced by high temperature
Phosphorescence-light produced through absorbing energy from another source
Electric Discharge-light produced by electricity passing through a gas [neon]
Fluorescence-light produced by using electric discharge and phosphorescence
Chemiluminescence-light produced by changing chemical energy into light energy
Bioluminescence-light produced by living things through a chemical process in their bodies

8. What is rectilinear propagation?
The idea that light travels in straight lines from a source.

9. What is the particle-wave duality?
The idea that light moves in both straight lines and in waves.

10. Degrees of Transparency
Material
Degree of Light
Examples
Transparent
Particles let light through easily; images are easy to see
Plastic wrap, glass, air, shallow water
Translucent
Particles let light in, but reflect light as well, making images not clear to see
Frosted glass, clouds, skin, fingernails
Opaque
Particles do not allow any light through; light is absorbed or reflected
Wood, stone, brick or most building materials

11. Compact Fluorescent Bulb vs. Incandescent Bulb
Contains a gas which produces UV light when electricity is added
Does not use heat to create light
More energy efficient than Incandescent bulbs
30% of energy emitted is heat
Creates light by heating a filament in the bulb
The energy used to create the heat is wasted
Has a shorter life span than CFB
90% of the energy emitted is heat

12. Reflection
Reflection occurs when light is returned after hitting a surface. Most surfaces reflect some light, otherwise we wouldn’t see them or their colour.
Rough surfaces reflect light in many directions, so we see very little light.

13. Reflecting Light
The Normal—the line drawn from the point of incidence at 900 to the surface of the optical device
Incident Ray—a ray of light that travels toward a reflecting surface
Angle of Incidence—is the angle between the incident ray and the normal
Angle of Reflection—the angle between the reflected ray and the normal
The point of incidence—the spot where the incident ray strikes the reflecting surface

14. Reflection Incident Ray Normal Angle of Incidence Angle of Reflection
Reflected Ray
Angle of Reflection
90 Degree Angle
Reflecting Surface [Mirror]

15. Laws of Reflection
The angle of incidence is equal to the angle of reflection
The incident ray, normal, and reflected ray all lie on the same plane

16. Plane Mirrors Plane mirrors always produce virtual images
The images of plane mirrors are always upright and located behind the mirror
Plane mirrors show the image of the object, not the object itself

17. Characteristics of Concave Mirrors
Concave mirrors “cave” inward
Concave mirrors can produce both real and virtual images
Concave mirrors focus parallel light rays
Concave mirrors can be used in devices to send light in a bean [flashlights]
Concave mirrors are used in reflecting telescopes to gather light from objects in space
Concave mirrors can produce a large image of a nearby object

18. Examples of Concave Mirrors
Cosmetic Mirrors
Solar Cookers
Reflecting Telescopes
Car headlights

19. Characteristics of Convex Mirror
Convex mirrors bulge outward
Convex mirrors always produce virtual images
Convex mirrors can be used to monitor large areas; it has a wider view than any other mirror
Convex mirrors always produce images that upright and smaller than the object

20. Examples of Convex Mirrors
Surveillance mirrors
School bus side mirrors
Cosmetic mirror for enlarging images

21. Light Facts Light travels in a straight line
Light travels at 300,000 km/s
When light hits a transparent surface, most of the light enters the material
Light refracting when it hits hot air creates mirages

22. Refraction: How does it work?
Light refracts when it travels from one material to another. Light refracts when it travels through air then hits a lens, or when it travels through air and hits water.

23. Refraction: How do materials effect refraction?
The speed of light differs from one material to another. The thicker the material, the slower the light travels. The change in speed causes the light to change direction.
Air=1.00
Water=1.33
Diamond=2.42

24. Refraction
Angle of Incidence is always greater than the Angle of Refraction
Angle of Incidence
NORMAL
Incident Ray
Angle of Refraction
Material of Refraction
Refracted Ray

25. What is Optics?
Optics is the science that studies the origin and spreading of light, how it changes, what effects it produces, and other phenomena associated with it.

26. What are the two branches of Optics?
Physical Optics—this branch is about the nature and properties of light
Geometrical optics—this branch is about the how images are formed with mirrors, lenses, and other optical devices

27. Optics Test Review
Write your answers on a long sheet of paper.

28. 1: List 3 examples of Convex Mirrors 3pts
Surveillance mirrors
School bus side mirrors
Cosmetic mirror for enlarging images

29. 2: What is one of the 2 laws of reflection? 4 pts
The angle of incidence is equal to the angle of reflection
The incident ray, normal, and reflected ray all lie on the same plane

30. 3: What are 3 ways to view light energy? 3 pts
Sun
Colour
Mirrors

31. 4: What are the density values for Air, Water and Diamonds? 3pts

32. 5: The line drawn from the point of incidence at 900 to the surface of the optical device is: 1pt
The Normal

33. 6: What are the 6 sources of light? 6pts
Incandescence
Phosphorescence
Electric Discharge
Fluorescence
Chemiluminescence
Bioluminescence

34. 7: The angle between the reflected ray and the normal is: 1 pt
Angle of Reflection

35. 8: What is the most important source of natural light? 1 pt
The Sun

36. 9: What are the 4 characteristics of an image? 4pts
Four characteristics of an image; size, attitude, location, and type.

37. 10: What are the 2 types of light bulbs? 2 pts
Incandescence and Compact Florescence

38. 11: How fast does light travel? 1pt
186,000 m/s or 300,000 km/s

39. 12: The spot where the incident ray strikes the reflecting surface is: 1pt
The point of incidence

40. 13: What are the 3 types of mirrors? 3pts
Plane
Concave
Convex

41. 14: Angles of incidence and reflection are always: 1pt
Equal

42. 15: Angle of Incidence is always _______ than the angle of Refraction: 1 pt
Greater than

43. 16: Write the formula to calculate the number of images seen in mirrors on angles: 1 pt
Number of images=(3600/angle between mirrors)-1

44. 17: What type of mirror can produce both real and virtual images? 1 pt
Concave mirror

45. 18: This type of bulb produces 30% of its energy as heat. 1pt
Compact Florescent

46. 19: List 3 examples of Concave mirrors: 3pts
Cosmetic Mirrors
Solar Cookers
Reflecting Telescopes
Car headlights

47. 20: Convex mirrors always produce_________ images: 1pt
Virtual