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Rays Flashcards

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1
Q

What can happen to waves (transverse or longitudinal) when they hit the boundary between 2 different materials?

A

Pass through the material completely unchanged (transmitted)
Pass through and change direction (refraction)
Absorbed by material
Reflected off the surface and not even enter the different material

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2
Q

What does a waves behaviour when it hits a boundary between materials tell us about the material?

A

Whether it can transmit a wave (pass through)
Absorb a wave (so it doesn’t pass through)
Reflect a wave

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3
Q

What does a materials interaction with waves depend on?

A

The material itself, what it’s made out of
The wavelength of the wave

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4
Q

How do light rays interact with glass mirrors?

A

They are reflected
So we can see our reflection

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5
Q

Light ray on a mirror reflection diagram description

A

Incident ray hits a mirror
Normal line is at right angles to the mirror
Angle between incident ray and normal line = angle of incidence

Reflected line will be at the same angle to the normal as the incident ray
Thus angle of reflection = angle of incidence

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6
Q

How do we use a ray diagram to show how an image will be reflected in a mirror? (Find its position)

A

Draw incident ray from object to mirror
Draw normal at right angles to the surface of the mirror
Draw reflected ray (at same angle)
include arrows
Draw another ray from the object + reflected ray
Extend the 2 reflected rays back into mirror, where they meet = position of reflected image

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7
Q

Refraction

A

When waves change direction from one medium to another
Because they change speed

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8
Q

What happens going from air —> glass for light rays?

A

They slow down
Thus blend towards the normal/ straighten up

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9
Q

When the light rays move from glass —> air?

A

The waves velocity increases/speeds up
And so bends away from the normal, in the same direction it was going before

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10
Q

What does refraction cause in an image?

A

For the image to shift in position

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11
Q

Exception to refraction

A

If a wave enters or leaves medium at right angles to it/ at the normal
It will not change direction

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12
Q

Wave front

A

Imaginary line that connects all the same points in a set of identical waves
Ie goes through the peaks of all waves

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13
Q

Refraction represented by wavefronts

A

The first wavefronts get closer together as they enter the new material
Showing a decrease in wavelength
So change direction towards normal
But when they leave the material they speed up
And so change direction away from normal = spread out

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14
Q

Wavefronts representing refraction perpendicular to the boundary

A

The waves will remain parallel to each other
But get closer together when they enter material/ decrease in velocity
And the whole wavefront line changes at the same time showing how they don’t change direction

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15
Q

Convex lenses

A

() shape
They focus parallel rays of light to a point called principle focus

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16
Q

Symbol of convex lens

A

Upwards arrow
⬆️

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17
Q

What do lens do?

A

Refract light
Ie change direction of rays when they move in and out

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18
Q

What do rays do if they pass through the centre of a lens?

A

Go straight through
Because it’s through the normal or principal axis
So they don’t change direction

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19
Q

What is the point called where all the rays of light meet together?

A

The principal focus aka F

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20
Q

Distance from centre of lens to principal focus name

A

Focal length

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21
Q

What determines the focal length amount?

A

The strength of the lens

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22
Q

When an object is at least 2 focal lengths away from convex lens diagram

A

One ray passes straight from the top of object through centre
Another line from top of object to the lens
This line to the lens is refracted to the focus
Where these 2 objects meet should be upside down = where the image is

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23
Q

When an object is at least 2 focal lengths away from lens description

A

The image is diminished
The image is inverted
The image is real because the rays actually meet at a point

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24
Q

When an object is between 2 focal lengths and one focal length from convex lens

A

Same as if it were 2
Line straight from top of image through centre
Line parallel to principle axis to the lens
This ray is refracted through the focus
Where these 2 rays meet = image

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25
Q

When an object is between 2 focal lengths and one focal length from convex lens description

A

Inverted
Enlarged
Real

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26
Q

So, what is the difference in outcome between position of object using convex lens

A

More than 2 focal lengths from lens =
DIMINISHED
Inverted
Real

BUT object is between 1 and 2 focal lengths =
MAGNIFIED
inverted
Real

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27
Q

What represents a magnifying glass?

A

Putting an object less than 1F away from the convex lens

28
Q

Ray diagram of object less than 1F away/ magnifying glass

A

Draw line straight through centre
Draw line from top of object parallel to the principle axis to the lens
This line then refracts through focus
These rays do not meet therefore we draw dotted lines to extend them behind the lens
They will meet = position of image

29
Q

Properties of image produced when magnifying glass/ object is 1F away from lens

A

Enlarged/magnified
Upright
Virtual as they are not made by real rays that meet at a point

30
Q

When do convex lens produce virtual images?

A

Only if it’s a magnifying glass
Aka less than 1F away

31
Q

What does it mean if an image is virtual?

A

It’s not real as the lens only appear to meet at a point
So it would not show up on a screen

32
Q

How to find magnification?

A

Image height / object height

33
Q

Concave lens

A

)( look like this
Make rays of light diverge ie spread out

34
Q

Symbol for concave lens

A

⬇️
⬆️

35
Q

Principle focus for concave lenses

A

If you continue the lines of the diverted rays
They join at a specific point = principal focus

36
Q

Do concave lens focus light at principle focus?

A

No they don’t actually because real rays do not join up there
They only appear to

37
Q

Ray diagram for concave lens

A

Ray line going straight through centre
Line parallel to principle axis hits the lens
Dotted line from focus to the line above
But hard line extended from it after passing through lens
Where they meet = image

38
Q

Concave lens image produced description

A

Upright
Diminished
Virtual

39
Q

Speculation reflection

A

When light reflects in a singular direction that is perpendicular to each other
Always on smooth surface aka mirror
Produces image

40
Q

Diffuse reflect

A

When light rays reflect in different directions to each other and scattered
On a rough surface
No image produced

41
Q

White light

A

Made up of the whole colour spectrum = a mixture

42
Q

What happens when white light passes through a prism

A

Splits into a spectrum

43
Q

What does the colour of an object depend on?

A

Which wavelengths of light are transmitted, reflected or absorbed
The colour the object is will reflect that wavelength and absorb all others

44
Q

How do colour filters work?

A

Absorb all other wavelengths and only transmit the specific one it is a filter of

45
Q

If an object can transmit light what does that mean?

A

You can see right through it
Aka glass

46
Q

Transparent

A

Easily see through

47
Q

Translucent

A

Scatter light rays
No see through able

48
Q

If an object can not be seen through what does that mean?

A

It is opaque

49
Q

Why do white objects appear white

A

Reflect all wavelengths of visible light equally

50
Q

Why do black objects appear black

A

Because they absorb all wavelengths of visible light equally

51
Q

Why do red objects appear red

A

Because it absorbs all wavelengths of visible light
Except frequency of red which is reflected

52
Q

Putting an object behind a filter of the same colour

A

Only that light wavelength allowed through
And then reflected off the object so still appears that colour

53
Q

Putting an object behind a filter of a different colour

A

The light wave will be absorbed by the object
So no light will be reflected
And appear black

54
Q

Best absorbers and emitters of infrared radiation

A

Matte black surfaces

55
Q

What object will emit more radiation in a given time?

A

A hot one over a cold one

56
Q

What does the wavelength and intensity of radiation depend on when emitted?

A

The temperature of the object

57
Q

What do hotter objects emit (infrared)

A

Higher intensity waves
Smaller wavelengths

58
Q

Why do very hot objects produce visible light?

A

Because they produce short length infrared radiation
So may even be visible light

59
Q

Black body radiation

A

All electromagnetic waves are absorbed
NONE is reflected nor transmitted
Also best possible emitter of them

60
Q

How do objects increase in temperature?

A

If it is originally colder than surroundings
It will absorb more radiation than emits

61
Q

How do objects decrease in temperature?

A

If it is originally hotter than surroundings
It will emit more radiation than absorbs so decreases

62
Q

How do objects remain at a constant temperature?

A

If at the same temp as surroundings, it will emit and absorb radiation at the same rate

63
Q

How does earth heat energy?

A

The sun emits short length radiation that can be reflected by clouds
Or absorbed by earth’s surface
To increase temperature

64
Q

What does earth do when absorbed sun’s infrared radiation?

A

Emits infrared radiation back into space
But some trapped by greenhouse gases so increases temperature

65
Q

What other factors affect earth temperature surface?

A

Cloud cover
Because more clouds will reflect infrared radiation back down to earth rather than radiating it to space

Physics (44 decks)

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