Physics Flashcards

1
Q

What are the four rules of reflection for both plane and curved mirrors?

A
  1. From the top of the object, through C (normal), which will reflect back over itself
  2. From the top of the object, parallel to the normal, then through F
  3. From the top of the object, through F, then parallel to the normal
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2
Q

Define Reflection

A

The change in direction of a light ray when it bounces off a surface

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3
Q

Define Medium

A

The substance through which light travels

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4
Q

Define Ray

A

A straight line with an arrowhead that shows the direction in which a light ray was travelling

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5
Q

Define Incident Ray

A

A beam of light coming from a light source traveling towards the normal

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6
Q

Define Angle of Incidence

A

Angle measurement from the incident ray to the normal

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7
Q

Define Normal

A

A hypothetical line perpendicular to a surface (drawn from wherever the incident ray hits the surface

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8
Q

Define Reflected Ray

A

Beam of light travelling away from the surface (the reflected incident ray)

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9
Q

Define Angle of Reflection

A

Angle measurement from normal to reflected ray

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10
Q

Define Virtual Image

A

An image formed by rays that appear to be coming from a certain position, but are not actually coming from that position; image does not form a visible projection in a screen (“behind” the medium)

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11
Q

Define Real Image

A

An image that is formed when reflected rays meet

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12
Q

What are the properties of Light

A

Light travels

  • in straight lines
  • very fast (300km/sec)
  • faster than sound
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13
Q

Why do we see things?

A

Objects reflect light into our eyes

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14
Q

In a rainbow, which colours have the longest and shortest wavelengths?

A

Red - longest wave length

Violet - shortest wave length

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15
Q

What is a concave mirror?

A

A reflecting surface curved inward

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16
Q

What is C?

A

The centre of curvature - the point in the circle where all normals will meet

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17
Q

What is the principal axis?

A

The horizontal normal that intersects with C

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18
Q

What is F?

A

The focal point - the point halfway between C and the mirror

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19
Q

Describe location and size - object is between F and the mirror

A

Upright and larger, virtual

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20
Q

Describe location and size - object is between C and F

A

Inverted and larger, real

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21
Q

Describe location and size - object is outside the center (past C)

A

Inverted and smaller, real

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22
Q

What is the first rule for concave mirrors?

A

Any line through C is a normal to the mirror (incident ray and reflected ray are the same)

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23
Q

What is the second rule for concave mirrors?

A

Any incident ray that is parallel to the principal axis will be reflected back through F

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24
Q

What is the third rule for concave mirrors?

A

Any incident ray that goes through F will be reflected back parallel to the principal axis

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25
What four things have to be identified about a reflected image in diagrams?
1. size (bigger or smaller) 2. orientation (upright or inverted) 3. distance from mirror (closer or farther away) 4. real or virtual
26
What is a convex mirror?
A reflecting surface curving outwards
27
How do images in convex mirrors appear?
Upright and smaller than the object, ALWAYS VIRTUAL
28
How do convex mirrors reflect images?
Outwards
29
How do concave mirrors reflect images?
Inwards
30
Describe Refraction
The bending of light when the light passes from one medium to another
31
When does light bend towards the normal?
When going from a less dense medium to a more dense medium
32
When does light bend away from the normal?
When going from a more dense medium to a less dense medium
33
What is the first law of refraction?
The incident ray, refracted ray, reflected ray and normal all lie in the same plane
34
What is the second law of refraction?
Index of Refraction: ratio of speed of light in a vacuum to speed of light in a given medium - passing from one medium to another, light bends and changes speed
35
What is "n"?
Index of Refraction
36
How does n correlate with density?
Directly - higher n = higher density
37
What is "c"?
The speed of light in a vacuum
38
What is the speed of light in a vacuum?
(3.00 x 10[8] m/s)
39
What is "v"?
The speed of light in a medium
40
What is the equation for n, c and v?
n = c/v
41
How does the index of refraction correlate with speed of light?
Inversely - increase in refractive index (and density) = decrease in speed
42
Is vacuum the least dense or most dense medium?
Least dense
43
As a beam of light becomes closer to being parallel to the surface of water, does more or less reflection occur?
More reflection - if the incident was along the normal, 100% refraction
44
Why do we see rainbows?
Because the speed of light changes when passing through raindrops
45
What is dispersion?
The process of separating colours by refraction of light through a prism
46
Why does a prism disperse white light into the spectrum of colours?
Each colour has its own wavelength and travels at a slightly different speed through the medium
47
What is the critical angle?
The angle at which the angle of incidence of a light ray produces a refracted ray along the surface of the medium
48
If an object is along the critical angle, do we see it?
No, the object is no longer visible
49
When does total internal reflection occur?
When the angle of incidence is greater than the critical angle, no refraction occurs
50
Why does light form just a circle on the surface when looking from underwater?
The light from overhead has a small angle of incidence and refracts to be visible to you. Light rays with higher angle of incidence than those will mostly reflect and will not be as visible
51
What is the appearance of a rainbow?
A multicoloured arc from red on the outer to violet on the inner
52
What causes rainbows?
Light is refracted entering the surface of the raindrop, reflected off the back of the drop and refracted as it leaves the drop, mostly from 40° to 42°; the amount of refraction depends on the wavelength of the light, hence its colour
53
What are the necessary conditions for a rainbow?
Water drops in the air and sunlight shining from behind at a low altitude angle
54
What is a lens?
A transparent object with at least one curved side that causes light to refract
55
What are the characteristics of lenses?
1. Transparent | 2. Either diverging or converging
56
What is a converging lens?
A lens that brings parallel light rays toward a common point as each ray refracts towards the normal when passing through the lens
57
What is a diverging lens?
A lens that causes parallel rays to spread away from a common point as each ray refracts towards the normal when passing through the lens
58
Where is the focal point for a converging lens?
the point on the principal axis through which the parallel rays converge
59
How is the focal point found for a diverging lens?
by tracing the diverging rays back to the principal axis
60
What is the diagram procedure for a converging lens?
1. Draw a parallel ray from the top of the object to the centre of the lens, then it will refract/converge through F 2. Draw a ray from the top of the object, through the center of the lens 3. Draw a ray from the top of the object through the focal point on the object's side to the centre of the lens, then it will refract parallel
61
What is the diagram procedure for a diverging lens?
1. Draw a parallel ray from the top of the object to the centre of the lens, then it will refract/diverge as though it's ray was passing through real F 2. Draw a ray from the top of the object, through the center of the lens 3. Draw a ray from the top of the object towards the focal point on the opposite side until the centre of the lens, then it will refract parallel
62
Describe the image with a converging lens - object is between F and the mirror
1. farther from the lens 2. upright 3. larger 4. virtual
63
Describe the image with a converging lens - object is between F and C
1. farther from the lens 2. inverted 3. larger 4. real
64
Describe the image with a converging lens - object is past C
1. closer to lens 2. inverted 3. smaller 4. real
65
Describe the image with a diverging lens
ALWAYS 1. closer to the lens 2. upright 3. smaller 4. real
66
What is chromatic aberration?
The fact that, with thick lenses, only rays near the principal axis will meet at the focal point
67
What is the difference between Galileo, Kepler and Newton's telescopes?
Galileo - converging and diverging lenses Kepler - only converging Newton - REFLECTING TELESCOPE; did not suffer from chromatic aberration
68
Describe Galileo's telescope
Converging lens as the objective lens, diverging lens as the eyepiece; low magnification but upright image
69
Describe Kepler's telescope
Converging lens for objective lens and eyepiece; increased magnification but created inverted image
70
Describe Newton's telescope
Light enters the telescope and travels to a concave mirror which reflects the light toward the focal point, then a plane mirror reflects towards the converging eyepiece
71
Describe Myopia
Near-sightedness: the eye focuses the image before it reaches the retina; the eye is too long and can't see distant objects
72
Describe Hyperopia
Far-sightedness: the eye focuses the image behind/past the retina; the eye is too short and cannot focus on near objects
73
How is myopia corrected?
A diverging lens is used to separate the rays and make them focus on the retina
74
How is hyperopia corrected?
A converging lens refracts the rays to make them focus on the retina