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Science 8 > Light & Optical Devices > Flashcards

Light & Optical Devices Flashcards

1
Q

How does light travel?

A

In straight lines.

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2
Q

What purpose do ray diagrams serve?

A

Because of the principle that light travels in straight lines, the ray diagram can help to explain certain properties of light.

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3
Q

What do scientists use ray diagrams for?

A

To show how light behaves.

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4
Q

Define ray.

A

A straight line which represents the path of a beam of light.

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5
Q

High intensity, lots or few light rays reaching the eye?

A

Lots.

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6
Q

Low intensity, lots or few light rays reaching the eye?

A

Few.

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7
Q

Few light rays reaching the eye, low or high intensity?

A

Low.

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8
Q

Lots of light rays reaching the eye, low or high intensity?

A

High.

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9
Q

What is an example of how the intensity of light changes?

A

Light intensity changes with distance from the source. For example, the closer you move a flashlight to your eye, the more rays will be reaching the eye, providing a higher intensity. The further away you move the flashlight, the fewer rays will reach the eye, providing a lower intensity.

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10
Q

How is a shadow created?

A

By the absence of light.

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11
Q

Why does an object in the way of rays of light form a shadow larger than the object?

A

Because it interferes where the rays are still spreading out (closer together), meaning it blocks more than if it were farther away. The other rays continue to spread out, leaving a large gap between them. The further the light goes, the larger the shadow gets. (Don’t quote me on that.)

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12
Q

How are shadows formed? (Model with a ray diagram on a piece of paper.)

A

Compare to the model on page 2 of the Topic 2 note package.

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13
Q

Draw a basic ray diagram (no lenses, shadows, mirrors, etc.)

A

Compare to the model on page 1 of the Topic 2 note package.

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14
Q

Why is the material an object is made of important when it comes to light?

A

When light strikes objects, it behaves in different ways depending on the type of material each object is made of.

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15
Q

What are examples of transparent materials? (2)

A
  1. Glass.

2. Clear plastics.

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16
Q

What can transparent materials do with regards to light?

A

They can transmit light, which means light travels straight through them.

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17
Q

How does light behave when traveling through transparent materials?

A

It travels straight through the materials.

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18
Q

What can translucent materials do with regard to light?

A

Allow some, but not all, light to pass through them.

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19
Q

How does light behave when traveling through translucent materials?

A

Some, but not all of it, passes through.

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20
Q

What can opaque materials do with regard to light?

A

They do not allow any light to pass through them (absorb/reflect the light that hits them, thus creating a shadow).

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21
Q

What is another word for opaque?

A

Solid.

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22
Q

What is another word for solid (material)?

A

Opaque.

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23
Q

How does light behave when traveling through opaque materials?

A

None of it manages to pass through - it either reflects or is absorbed; a shadow is formed.

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24
Q

Define luminous.

A

Anything that produces light; a light source.

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25
Q

Define non-luminous.

A

Objects that do not produce light; objects that are not light sources.

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26
Q

What are the types of reflection? (2)

A
  1. Regular reflection.

2. Diffuse reflection.

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27
Q

When does regular reflection occur?

A

When a light ray hits a smooth surface.

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28
Q

When does diffuse reflection occur?

A

When a light ray hits an uneven surface.

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29
Q

Explain what regular reflection looks like.

A

All the rays are reflected at the same angle, producing a clear image. Your eyes must be in the direct path of the reflected rays in order to see the reflected image.

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30
Q

Explain what diffuse reflection looks like.

A

When light rays strike an uneven surface, each ray is reflected at a different angle.

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31
Q

Draw a ray diagram of how the intensity of light changes with distance.

A

Compare to the model on page 1 of the Topic 2 note package.

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32
Q

Draw a ray diagram of regular reflection.

A

Compare to the model on page 3 of the Topic 2 note package.

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33
Q

Draw a ray diagram of diffuse reflection.

A

Compare to the model on page 4 of the Topic 2 note package.

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34
Q

Define plane mirrors.

A

Flat mirrors, provide the clearest reflections in regular reflection.

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35
Q

How can you make a regular reflection produce a more clear image?

A

The shinier and smoother the surface, the better the reflection. Plane mirrors (flat mirrors) provide the clearest reflections.

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36
Q

Define angle of incidence.

A

The angle between the incident ray and the normal line.

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37
Q

Define angle of reflection.

A

the angle between the reflected ray and the normal line.

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38
Q

Define normal line.

A

The imaginary line parallel to the surface of which an incidence ray is bouncing off.

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39
Q

What is the ray called that hits the surface prior to reflection?

A

Incidence ray.

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40
Q

What is the ray called that bounces off of the surface due to reflection?

A

Reflected ray.

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41
Q

Draw a ray diagram depicting a mirror, the normal line, and the ray bouncing off of the mirror.

A

Compare to the model on page 4 of the Topic 2 note package.

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42
Q

What does the Law of Reflection state?

A

According to the Law of Reflection, the angle of incidence is equal to the angle of reflection.

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43
Q

Is the angle of incidence/reflection measured from the surface or from the normal line?

A

From the normal line.

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44
Q

Define concave.

A

Has a surface that curves inward.

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45
Q

Define convex.

A

Has a surface that curves outward.

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46
Q

Do concave mirrors obey or defy the law of reflection?

A

Obey.

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47
Q

How does a focal point form with a concave mirror?

A

When parallel light rays approach a curved surface and strike at different points on the curve, each ray will reflect in a slightly different direction. These rays all head to a common point called the focal point. This is where they meet/cross.

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48
Q

Draw a ray diagram depicting the creation of a focal point after rays hit a concave mirror.

A

Compare to the model on page 5 of the Topic 2 note package.

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49
Q

What does the image formed by a concave mirror depend on?

A

How far the object is away from the mirror.

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50
Q

When dealing with a concave mirror, what happens if the object is far away from the focal point?

A

The reflected rays form an upside-down image, that is also smaller.

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51
Q

When dealing with a concave mirror, what happens if the object gets closer to the focal point?

A

The closer the object gets to the focal point, the larger the image becomes. It remains upside down.

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52
Q

When dealing with a concave mirror, what happens if the object is between the focal point and the mirror?

A

The reflected image becomes upright and enlarged.

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53
Q

Draw 3 ray diagrams depicting the formation of an image through reflected rays after being reflected off of a concave mirror. (Object far from the focal point, object close to the focal point, object past the focal point.)

A

Compare to the model on page 6 of the Topic 2 note package.

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54
Q

A concave mirror is less curved. Focal point: further or closer from the mirror?

A

Further.

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55
Q

A concave mirror is more curved. Focal point: further or closer from the mirror?

A

Closer.

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56
Q

The focal point of a concave mirror is far away. Mirror: more or less curved?

A

Less.

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57
Q

The focal point of a concave mirror is closer. Mirror: more or less curved?

A

More curved.

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58
Q

How is a concave mirror efficient in a flashlight?

A

It produces a parallel beam.

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59
Q

How is a concave mirror efficient in a telescope?

A

Collects a large amount of light from a distant source and focuses it for viewing.

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60
Q

How is a concave mirror efficient in a cosmetic mirror?

A

Produces an enlarged image.

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61
Q

How is a concave mirror efficient in car headlights?

A

Produces a parallel beam of light that can be directed down (low beam) or straight ahead (high beam).

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62
Q

What does a convex mirror do?

A

It spreads out light rays; the opposite of what a concave mirror does.

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63
Q

Draw a ray diagram depicting the formation of a focal point with a convex mirror.

A

Compare to the model on page 8 of the Topic 2 note package.

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64
Q

What happens when light leaves water?

A

It bends.

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65
Q

Define interface.

A

A boundary where two different substances meet.

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66
Q

What happens when a light ray strikes an interface at an angle?

A

It will change direction. (Bends/refracts)

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67
Q

How come light bends when leaving water?

A

When a light ray strikes a boundary where two different substances meet (interface) at an angle, it will change direction.

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68
Q

Draw a diagram depicting how light bends when leaving the water.

A

Compare to the model on page 9 of the Topic 2 note package.

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69
Q

Define medium.

A

A substance or material.

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70
Q

Define refraction.

A

The bending of light; due to changes in the speed of light.

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71
Q

What does it take for light to refract?

A

It needs to strike a medium of different density at an angle. Then it will refract.

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72
Q

How does the density of a medium affect how light refracts? Provide an example.

A

The denser the new medium, the more the light slows down, and so the more it refracts.

For example: a diamond is much denser than water, and so a diamond refracts light more than water does.

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73
Q

Define lens.

A

A piece of curved glass or transparent material.

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74
Q

How are lenses shaped and why?

A

They are smooth and regularly shaped so that when light strikes them, the light refracts in a predictable way.

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75
Q

Why do lenses need to be smooth and regularly shaped?

A

So that we can predict how the light will refract when it strikes.

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76
Q

What happens when light passes through a concave lens?

A

As light passes through a concave lens, the light rays diverge (spread out); they will never meet on the other side of the lens.

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77
Q

Draw a ray diagram depicting where the focal point WOULD be with a concave lens.

A

Compare to the diagram on page 11 of the Topic 2 note package.

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78
Q

Define diverge.

A

Spread out.

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79
Q

Define double convex lens.

A

The technical name for a convex lens that curves outward on both sides.

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80
Q

What is the technical name for a convex lens that curves outward on both sides?

A

A double convex lens.

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81
Q

Explain what happens when light passes through a convex lens. (2)

A
  1. Parallel rays move towards each other.

2. The light rays cross at the focal point.

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82
Q

How can you alter where the focal point is with a convex lens? (2)

A

Either…

  1. By changing the curvature of the lens.
  2. By changing the substance it is made of.
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83
Q

What are convex lenses useful for? (2)

A
  1. it can act as a light collector (much like a concave mirror). This is why a convex lens is used in a refracting telescope. It collects and focuses starlight.
  2. A convex lens forms a real image. The light rays actually meet at a point, and the image can be projected onto a screen.
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84
Q

What is most likely to be found in a movie theatre projector?

A

A convex lens.

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85
Q

What is most likely to be found in a refracting telescope?

A

A convex lens.

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86
Q

What is most likely to be found in a flashlight?

A

A concave mirror.

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87
Q

What is most likely to be found in a telescope?

A

A concave mirror.

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88
Q

What is most likely to be found in a cosmetic mirror?

A

A concave mirror.

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89
Q

What is most likely to be found in car headlights?

A

A concave mirror.

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90
Q

How can you change the size of a projected image using a convex lens? (The lens projecting the image, not being used to alter the size.)

A

Depending on how far an object is from the lens, you can project images that are smaller or larger than the object.

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91
Q

What is the downside to convex lenses?

A

The image is upside down.

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92
Q

How will the projection look if the object is farther away than the focal point of the convex lens?

A

Upside down and smaller.

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93
Q

How will the projection look if the object is moved closer to the focal point of the convex lens?

A

The image appears upside down and larger.

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94
Q

How will the projection look if the object passes the focal point of the convex lens?

A

Upright and larger, and it will form on the same side of the lens as the object originally was.

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95
Q

Draw 3 ray diagrams depicting the formation of an image through reflected rays after being refracted through a convex lens. (Object far from the focal point, object close to the focal point, object past the focal point.)

A

Compare to the model on the last page of the Topic 2 note package.

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96
Q

What are models based on?

A

What we observe about the characteristics and properties of something.

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97
Q

What do models do?

A

They help make it easier to understand complex concepts.

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98
Q

Which model do scientists commonly use?

A

The wave model of light.

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99
Q

What is the advantage of using a ray model?

A

Simplicity.

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100
Q

What is the advantage of using a wave model?

A

Colour is described naturally in terms of wavelenth.

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101
Q

What is a wave model required for?

A

In order to explain the interaction of light with material objects of sizes comparable to or smaller than a wavelength of light.

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102
Q

What is a particle model required for?

A

In order to explain the interaction of light with individual atoms. At the atomic level, it becomes apparent that a beam of light has a certain graininess to it.

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103
Q

What are the types of wave models of light? (3)

A
  1. Ray model.
  2. Wave model.
  3. Particle model.
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104
Q

What does thinking about light traveling in waves help with? Provide two examples.

A

It helps to explain unpredictable behaviour. Like when…

  1. Light curves around an opening.
  2. When light passes through a small opening, the waves spread out.
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105
Q

What happens when light passes through a small opening?

A

The waves spread out.

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106
Q

What are the two major similarities between waves and light?

A
  1. Both are forms of energy.

2. They travel out in all directions.

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107
Q

Define amplitude.

A

The height of a wave from the rest point to the crest (highest point).

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108
Q

Define crest.

A

The highest point of a wave.

109
Q

Define wavelength.

A

The distance from the crest of one wave to the crest of the next (or from two identical parts to one another.)

110
Q

Define frequency.

A

The number of times the medium vibrates in a given unit of time.

111
Q

What are waves/second referred to as?

A

Hertz (Hz).

112
Q

More Hz. Frequency increases or decreases?

A

Increases.

113
Q

Less Hz. Frequency increases or decreases?

A

Decreases.

114
Q

More Hz. Energy increases or decreases?

A

Increases.

115
Q

Less Hz. Energy increases or decreases?

A

Decreases.

116
Q

Higher frequency. Energy increases or decreases?

A

Increases.

117
Q

Lower frequency. Energy increases or decreases?

A

Decreases.

118
Q

Higher frequency. Wavelength increases or decreases?

A

Decreases.

119
Q

Lower frequency. Wavelength increases or decreases?

A

Increases.

120
Q

Longer wavelength. Frequency higher or lower?

A

Lower.

121
Q

Shorter wavelength. Frequency higher or lower?

A

Higher.

122
Q

What happens as the frequency increases with regard to the wave?

A

The crests of each wave are closer to one another, decreasing the wavelength.

123
Q

What do you need to create a rainbow?

A

Sunlight.

124
Q

What happens when you shine sunlight/white light through a prism?

A

The light refracts, and splits up into the colours of the rainbow. Each colour of light is refracted at a different angle. So white light is made up of many different colours of light.

125
Q

What do the colours in light form?

A

The visible light spectrum.

126
Q

What is the visible light spectrum formed by?

A

The colours that make up white light.

127
Q

What is the relationship between refraction and wavelength when shining white light through a prism?

A

Longer wavelength refracts less. Shorter wavelength refracts more.

128
Q

What is the wavelength between (nm) when it comes to the colours of visible light?

A

Between 700nm (nanometres) for red and 400 nm (nanometres) for violet.

129
Q

What are the types of light? (Lowest to highest wavelength.)

A

Radiowaves -> microwaves -> inferred -> visible light -> Ultra-violet rays -> x-rays -> gamma rays.

130
Q

What are radio waves used for?

A

Used in telecommuniction and medicine. Radio waves are used in MRI machines to construct images by exciting particles inside tissues.

131
Q

What are microwaves used for?

A

Interact with water to create friction in the molecule. They are also used in RADAR, where microwaves are sent out and reflected off of objects (ships, airplanes, or clouds for weather systems).

132
Q

What are infrared waves used for?

A

Can be detected with infrared or night vision goggles or measured by thermometer. These images form what is called a thermogram.

133
Q

What are ultraviolet rays used for?

A

It is the first ionizing or carcinogenic (can cause Cancer) light. UV lights are used in medicine to sterilize equipment. We need small doses of UV light to form vitamin D (SAD).

134
Q

What are x-rays used for?

A

We primarily use x-rays for medical scanning as the light will pass through tissues but reflect off of dense objects such as bones.

135
Q

What are gamma rays used for?

A

Will penetrate all body tissues and cause injury. Applications include surgery without incision (gamma knife).

136
Q

Which type of EMR does the sun release?

A

All tyes. Thankfully, most due to our atmosphere and magnetic field, most EMR gets blocked.

137
Q

What does EMR stand for?

A

Electromagnetic Radiation.

138
Q

Define artificial sources.

A

Light sources that are manmade.

139
Q

What are light sources that are manmade known as?

A

Artificial sources.

140
Q

Who was the first person to design the light bulb? When?

A

Thomas Edison. In the 1800s.

141
Q

What do we use as a filament in light bulbs? What did Edison use?

A

Edison used bamboo, so they didn’t last long. We now use tungsten.

142
Q

What are the types of artificial sources we are concerned with? (3)

A
  1. Fluorescent.
  2. Phosphorescent.
  3. Incandescent.
143
Q

How do incandescent bulbs work?

A

They are glass bulbs with a thin wire (filament) running through them. As the electricity runs through it, heat and light are produced causing the wire to glow.

144
Q

Why are incandescent bulbs inefficient?

A

A lot of the energy is lost to heat.

145
Q

How do fluorescent bulbs work?

A

It is a glass tube filled with a small amount of gas such as mercury vapour. It is also coated with a white powder called phosphor. When electricity passes through the bulb, it strikes the phosphor and creates white light.

146
Q

What is the emission of white light through a fluorescent bulb known as?

A

“Fluorescing”.

147
Q

Define phosphorescence.

A

The ability to emit light long after EMR has stopped hitting it.

148
Q

How does phosphorescent material work?

A

It “glows in the dark” and recharges when exposed to light.

149
Q

What are the factors that the choice between artificial light sources depends on? (5)

A
  1. Convenience.
  2. Appearance.
  3. Cost.
  4. Efficiency.
  5. Durability.
150
Q

What is the colour difference between fluorescent and incandescent?

A

Fluorescents tend to be very bright white light, while incandescents tend to be more yellow, or warm in tone.

151
Q

How efficient are incandescents?

A

Lose 95% of their energy to heat.

152
Q

How efficient are fluorescent bulbs?

A

Lose 80% of their energy to heat.

153
Q

How efficient are halogens and LED’s?

A

Lost 10-20% of their energy to heat.

154
Q

How does heat escape the bulb?

A

As infrared radiation.

155
Q

Define bioluminescence.

A

When living organisms possess the ability to produce their own light.

156
Q

How does bioluminescence work?

A

It involves the organism having a light-producing organ that houses a chemical reaction that creates light.

157
Q

What is the function of bioluminescence?

A

Can vary from mate selection to hunting.

158
Q

What are the primary colours of light? (3)

A
  1. Red.
  2. Green.
  3. Blue.
159
Q

What happens when you mix red, blue, and green light together?

A

You get white light.

160
Q

What is the theory of colour addition?

A

That when you mix red, blue, and green light, you get white light.

161
Q

How does the theory of colour addition work?

A

Different wavelength collide with one another, creating an interference pattern, which makes a new wavelength; the wavelength of white light.

162
Q

What happens when you combine only two of the three primary colours of light?

A

You can make a host of different colours.

163
Q

Define secondary colour.

A

The product these two additive colours creates.

164
Q

Red + green =

A

Yellow.

165
Q

Red + blue =

A

Magenta.

166
Q

Blue + green =

A

Cyan.

167
Q

How do TVs produce colours? (3)

A
  1. Every TV has small rows which emit different amounts of green, bue, or red light.
  2. When coordinated wit neighbouring cells, you produce a colour image.
  3. By having different amounts of these colours cells glow at one time, you can produce any colour we can see.
168
Q

What parts of the eye did we study? (8)

A
  1. Cornea.
  2. Iris.
  3. Pupil.
  4. Lens.
  5. Ciliary muscle.
  6. Retina.
  7. Optic nerve.
  8. Blood vessels.
169
Q

Where is the cornea located?

A

It is on the very front of the eye.

170
Q

Where is the iris located?

A

Underneath the cornea; is the colored portion of our eye.

171
Q

Where is the pupil located?

A

It is a hole inside the iris that lets light fall through the lens; so it is positioned between them.

172
Q

Where is the lens located?

A

Underneath the iris and the pupil.

173
Q

Where is the ciliary muscle located?

A

To the sides of the lens; it adjust the thickness of the lens.

174
Q

Where is the retina located?

A

On the back wall of the eye.

175
Q

Where is the optic nerve located?

A

In a channel stemming out from the back wall of the eye.

176
Q

Where are the blood vessels of the eye located?

A

Reaching from the back of the eye inwards.

177
Q

What is the alikeness between a human eye and a camera?

A

They use the same method of allowing a light through a hole. In an eye, this is called the pupil. In a camera, it is called an aperture.

178
Q

How does a camera let light through a hole?

A

Using the aperture.

179
Q

How does a human eye allow light through a hole?

A

Using the pupil.

180
Q

Define iris.

A

A circular band of muscle.

181
Q

Define pupil.

A

A hole created by the iris.

182
Q

What does the iris do?

A

It controls the size of the pupil, and so regulates the amount of light that enters the eye.

183
Q

What happens to the iris and the pupil in dim light?

A

The iris opens and the pupil dilates (becomes wider) to let in more light.

184
Q

What happens to the iris and the pupil in bright light?

A

The iris closes and the pupil constricts (becomes smaller) to let less light in.

185
Q

Define dilate.

A

When the pupil becomes wider and lets in more light.

186
Q

Define constrict.

A

When the pupil becomes smaller in order to let less light in.

187
Q

How do we see? (4 steps)

A
  1. Light rays must strike the sensitive retina at the back of the eye. The retina is a special layer that is filled with photoreceptors -> cells that are sensitive to light.
  2. When light strikes the retina, photoreceptors are stimulated, and they send messages to the optic nerve.
  3. The optic nerve passes the message to the brain.
  4. The brain translates the messages into actions.
188
Q

Define retina.

A

A special layer that is filled with photoreceptors.

189
Q

Define photoreceptors.

A

Cells that are sensitive to light.

190
Q

How do rods function in low light?

A

They are highly sensitive to light; even in small amounts.

191
Q

What do cones do?

A

Cones detect colour, but they can’t function in low light, so all we see are shades of grey in the dark.

192
Q

How do film cameras work?

A

At the back of the camera is light-sensitive film. When light strikes the film, the film changes chemically, forming an image.

193
Q

How does the eye change the shape of the lens?

A

Mucles attached to the lens relax or contract to change the shape of the lens.

194
Q

Why do we change the shape of the lens?

A

It adjusts the focal length so that light forms a focused image on the retina.

195
Q

How do you adjust the focal length on a camera?

A

In automatic cameras, the lens is automatically moved forward or backward to adjust the focal length. On a manual camera, this movement is done by hand.

196
Q

How come we don’t see upside down?

A

Although the image formed on the retina is upside down, your brain corrects this and interprets the world right-side up.

197
Q

What is farsightedness?

A

When you cannot see close objects clearly.

198
Q

What causes farsightedness?

A

The eye cannot make the lens fat enough to focus light on the retina, and the image falls behind the retina.

199
Q

What is near-sightedness?

A

When the eye cannot make the lenWhen you cannot see far objects clearly.

200
Q

What causes near-sightedness?

A

The eye cannot make the lens thin enough to focus light on the retina, and the image falls in front of the retina.

201
Q

What type of lens is prescribed to people whose lenses cannot converge light enough (focuses light after the retina)?

A

Convex lenses.

202
Q

What type of lens is prescribed to people whose lenses focus light before it reaches the retina?

A

Concave lenses.

203
Q

Define laser eye surgery.

A

Surgeons use a laser to reshape the cornea of the eye. This makes it possible to see clearly without wearing lenses or contacts.

204
Q

How do night vision goggles work? (5 steps)

A
  1. Light is focused onto an image intensifier.
  2. Inside the intensifier, the light energy releases a stream of particles.
  3. These particles then hit a phosphor-coated screen.
  4. The phosphors glow green when the particles strike them.
  5. The person wearing the goggles sees a glowing green image.
205
Q

What are the characteristics of camera eyes? (4)

A
  1. Have a cornea.
  2. Have a lens.
  3. Have a retina.
  4. Are roughly round in shape.
206
Q

What are vertebrates?

A

Animals with backbones.

207
Q

What are invertebrates?

A

Animals without backbones.

208
Q

Who usually has camera eyes?

A

Vertebrates.

209
Q

What type of eyes do vertebrates usually have?

A

Camera eyes.

210
Q

What does the structure of a camera eye depend on?

A

Depending on how the animal uses the eye, the structure of the camera eye can vary slightly.

211
Q

What kind of eyes do fish have? How does this help them?

A

They have camera eyes. which have perfectly round lenses. Because the lenses stick out, a fish can see in every direction. This is useful because the fish have no necks and can’t swivel their heads to look for danger.

212
Q

What types of cones do humans have? (3)

A

One type senses red light, one senses blue light, and one senses green light.

213
Q

How many types of cones do humans have?

A

3.

214
Q

How many types of cones do birds have? What does this mean?

A

Five different types, each sensitive to a different wavelength of light. This means that birds can distinguish more colours and shades than humans can.

215
Q

Define nocturnal.

A

Animals who can see in complete darkness.

216
Q

How do nocturnal animals see in the dark? (3)

A
  1. Cats and owls have very large pupils, which allow in as much light as possible.
  2. They have a layer inside their eyes called the tapetum lucidum, which acts as a mirror to reflect light inside their eyes.
  3. Nocturnal animals have more rods than cones in their retinas. Rods are far more sensitive to low levels of light.
217
Q

What does the tapetum lucidum do?

A

It is a layer inside the eyes of cats and owls, which acts as a mirror to reflect light inside their eye.

218
Q

What are compound eyes made up of?

A

Each eye is made up of small units.

219
Q

What are the individual units in compound eyes called?

A

Ommatidum.

220
Q

What is an ommatidum?

A

The individual units on compound eyes.

221
Q

How are ommatidia formed?

A

They look like long tubes with lenses on the outer surface, a focusing cone below it, and a light-sensitive cell below that.

222
Q

How do the compound eyes of most insects look?

A

Insect eyes tend to have a convex surface, so ommatidia lenses face in almost all directions.

223
Q

What is the advantage of compound eyes?

A

The compound eye is great at spotting motion.

224
Q

What is the disadvantage of compound eyes?

A

Multiple lenses make it difficult to form a single coherent image.

225
Q

What does the image formed by a compound eye resemble?

A

The image is somewhat like a TV screen.

226
Q

What does your brain play a role in when it comes to images you have seen? (3)

A

Information…

  1. Sorting.
  2. Storing.
  3. Retrieving.
227
Q

What do photographic negatives and film rely on?

A

Chemicals to store information.

228
Q

What can happen overtime when it comes to photographic negatives and film?

A

Over time, chemicals can react and change.

229
Q

How is most information today stored?

A

Digitally. You take any form of information and convert it into numbers.

230
Q

Define digital imaging.

A

The process of creating a big picture out of small pieces.

231
Q

How do you store images digitally? (4)

A
  1. When a computer receives an image, it divides the picture up into small elements called pixels.
  2. Each pixel is assigned coordinates, just like the row and seat numbers for a stadium seat.
  3. Now the computer has reduced the picture to a series of numbers.
  4. This long series of numbers can be stored and saved in a computer.
232
Q

How do you color a digital image?

A

In digital imaging, the computer assigns a value to each pixel. This number corresponds to a certain colour. When the picture is assembled, the computer reads the value and makes the pixel that particular colour. If an image is black and white, the value assigned to each pixel corresponds to a shade of grey instead of a colour.

233
Q

Define resolution.

A

The quality of a digital image depends on the size of pixels that make up the image. The more pixels, the higher the resolution, and the clearer it will look. The resolution of an image refers to the number of pixels per unit area.

234
Q

List three things that use the same method of captured images (capturing digital images).

A
  1. Phone camera/digital camera.
  2. TV and computer screens.
  3. Photocopiers.
235
Q

What does light fall on in digital cameras instead of film?

A

It lands on a charged-coupled device (CCD).

236
Q

Who was Pythagoras?

A

He was a mathematician who tried to explain how we see light.

237
Q

What was Pythagoras’ theory? What was the error in this theory?

A

Based on the idea that lights are made up of beams, he thought that light comes from our eyes; one sees light when beams come in contact with the object one is viewing. The error is that this means that we should e able to see in the dark.

238
Q

Who was Ptolemy?

A

He was an astronomer.

239
Q

What did Ptolemy figure out?

A

He figured out and described how light beams bend when converting from air to glass.

240
Q

What did Euclid discover? (2)

A
  1. Proposed that the movement of light is in straight lines.
  2. Found out that when in contact with a flat-surfaced mirror, the angle between the light’s beam and the mirror is equal to the angle between the mirror and the beam that is being reflected.
241
Q

What did al-Haytham discover?

A

Studied works of Euclid and Pythagoras. Replaced Pythagoras’ theory: light doesn’t come from the eyes; it bounces off of objects and then moves on to the eyes.

242
Q

What did Hans and Zacharias Jansen do?

A

They built a microscope (believed to be the first). Though the first microscopes were simpler than modern-day ones, they were promising for new discoveries and led to biology.

243
Q

What did Van Leeuwenhook discover?

A

Experimented with a microscope and discovered things no one was aware of; bacteria, algae, protozoa, and red blood cells. This sparked microbiology.

244
Q

What did Newton discover?

A

Experimented and figured out that white light is a mixture of colourful lights. When shone through a prism, white light split into colourful lights. Colourful lights formed white light.

245
Q

What did Romer discover?

A

Placed two mirrors on mountains in California. 35.4km apart. Romer sent a beam of light from one mirror to the other, measuring how long it took for the light to reach the other side with relatively accurate timing devices. Conclusion: 299798km/s.

246
Q

What did Galileo discover?

A

Began building his own telescopes after hearing about the invention, more improved each time. Magnification allowed him to discover that Venus has phases. Light-collecting ability showed objects circling Jupiter. Saw mountains and craters on the moon.

247
Q

Who was Michelson?

A

Albert A. Michelson was a scientist.

248
Q

What did Michelson do?

A

He improved Romer’s measurement to make it more accurate.

249
Q

Who…

Based on the idea that lights are made up of beams, he thought that light comes from our eyes; one sees light when beams come in contact with the object one is viewing. The error is that this means that we should e able to see in the dark.

A

Pythagoras.

250
Q

Who…

He figured out and described how light beams bend when converting from air to glass.

A

Ptolemy.

251
Q

Who…

  1. Proposed that the movement of light is in straight lines.
  2. Found out that when in contact with a flat-surfaced mirror, the angle between the light’s beam and the mirror is equal to the angle between the mirror and the beam that is being reflected.
A

Euclid.

252
Q

Who…

Studied works of Euclid and Pythagoras. Replaced Pythagoras’ theory: light doesn’t come from the eyes; it bounces off of objects and then moves on to the eyes.

A

Al-Haytham.

253
Q

Who…

They built a microscope (believed to be the first). Though the first microscopes were simpler than modern-day ones, they were promising for new discoveries and led to biology.

A

Jansen. Hans and Zacharias Jansen.

254
Q

Who…

Experimented with a microscope and discovered things no one was aware of; bacteria, algae, protozoa, and red blood cells. This sparked microbiology.

A

Van Leeuwenhook.

255
Q

Who…

Experimented and figured out that white light is a mixture of colourful lights. When shone through a prism, white light split into colourful lights. Colourful lights formed white light.

A

Newton.

256
Q

Who…

Placed two mirrors on mountains in California. 35.4km apart. Romer sent a beam of light from one mirror to the other, measuring how long it took for the light to reach the other side with relatively accurate timing devices. Conclusion: 299798km/s.

A

Romer.

257
Q

Who…

Began building his own telescopes after hearing about the invention, more improved each time. Magnification allowed him to discover that Venus has phases. Light-collecting ability showed objects circling Jupiter. Saw mountains and craters on the moon.

A

Galileo.

258
Q

Who…

Improved Romer’s measurement to make it more accurate.

A

Michelson.

259
Q

What time was Pythagoras?

A

6th century B.C.

260
Q

What time was Ptolemy?

A

1st century A.D.

261
Q

What time was Euclid?

A

1st-3rd century A.D.

262
Q

What time was al-Haytham?

A

1000 A.D.

263
Q

What time was Jansen?

A

1595.

264
Q

What time was Van Leeuwenhook?

A

17th century.

265
Q

What time was Newton?

A

1665.

266
Q

What time was Romer?

A

1676.

267
Q

What time was Galileo?

A

Late 17th century.

268
Q

What time was Michelson?

A

1920s.

Science 8 (3 decks)

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