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X GCSE Physics - outdated and incomplete due to advanced information 2022 > P14 - Light > Flashcards

P14 - Light Flashcards

1
Q

What is the angle of incidence?

A

The angle between the incident ray and the normal

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2
Q

What is the angle of reflection?

A

Angle between the reflected ray and the normal

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3
Q

What is a concave lens?

A

A lens that makes parallel rays diverge (spread out)

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4
Q

What is a convex lens?

A

A lens that makes light rays parallel to the principal axis converge (meet) at a point

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5
Q

What is diffuse reflection?

A

Reflection from a rough surface - the light rays are scattered in different directions

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6
Q

What is the focal length?

A

The distance from the centre of the lens to the point where light rays parallel to the principal axis are focused

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7
Q

What is magnification?

A

image height / object height

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8
Q

What is a magnifying glass?

A

A converging lens used to magnify a small object which must be placed between the lens and its focal point

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9
Q

What is the normal?

A

A straight line through a surface or boundary perpendicular to the surface or boundary

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10
Q

What is an opaque object?

A

An object which light cannot pass through, instead the object absorbs or reflects the light

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11
Q

What is the principal focus?

A

The point where light rays parallel to the principal axis of a lens are focused for a convex lens, and where the light rays appear to originate from for a concave lens

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12
Q

What is a real image?

A

An image formed by a lens that can be projected onto a screen

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13
Q

What is refraction?

A

The change of direction of a light ray as it passes across a boundary between 2 transparent substances

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14
Q

What is specular reflection?

A

Reflection from a smooth surface. Each light ray is reflected in a single direction

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15
Q

What is a translucent object?

A

An object that allows light to pass through, but the light is scattered or refracted as it does so, due to lots of internal boundaries in the object

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16
Q

What is a transparent object?

A

An object that transmits all the incident light that enters the object

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17
Q

What is a virtual image?

A

An image, seen in a lens or a mirror, from which light rays appear to come after being refracted by a lens or reflected by a mirror. They cannot be projected onto a screen

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18
Q

When would sound be relfected?

A

In an echo

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19
Q

What is the law of reflection?

A

The angle of incidence = the angle of reflection

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20
Q

What is reflection on a smooth surface known as and why?

A

Specular reflection, this is because parallel light rays are reflected in a single direction, they are not scattered. Each of the incident angles are the same, therefore each of the angles of reflection are the same

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21
Q

What is reflection on a rough surface known as and why?

A

diffuse reflection, this is because parallel light rays reflected from a rough surface are scattered in different directions. Each of the incident angles are different, therefore each of the angles of reflection are different

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22
Q

What happens to the velocity of a wave as it travels from an optically rare medium to an optically dense medium?

A

decreases

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23
Q

What happens to the wavelength of a wave as it travels from an optically rare medium to an optically dense medium?

A

Decreases

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24
Q

What happens to the frequency of a wave as it travels from an optically rare medium to an optically dense medium?

A

does not change

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25
Q

What happens to the direction of a wave as it travels from an optically rare medium to an optically dense medium?

A

bends towards the normal

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26
Q

What happens to the velocity of a wave as it travels from an optically dense medium to an optically rare medium?

A

increases

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27
Q

What happens to the wavelength of a wave as it travels from an optically dense medium to an optically rare medium?

A

increase

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28
Q

What happens to the frequency of a wave as it travels from an optically dense medium to an optically rare medium?

A

Does not change

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29
Q

What happens to the direction of a wave as it travels from an optically dense medium to an optically rare medium?

A

bends away from the normal

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30
Q

What causes refraction?

A

Waves change speed as they pass between substances of different densities, this causes them to change direction

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31
Q

What is the law of refraction?

A
  • If the light ray moves from a less dense medium into a dense medium, the wave bends towards the normal. Therefore the angle of refraction is smaller than the angle of incidence
  • If the light ray moves from a more dense medium into a less dense medium, the wave bends away from the normal. Therefore the angle of refraction is greater than the angle of incidence
32
Q

Describe what occurs when light travels from air into a glass block and then back out into air:

A

When light enters the glass block, it slows down, this is because glass is more dense than air. The wavelength of the light ray decreases and the direction of the wave moves towards the normal. As the ray moves out of the glass block into air it speeds up, this is because air is less dense than glass. The wavelength of the light ray increases and the direction moves away from the normal line.

32
Q

Describe what occurs when light travels from air into a glass block and then back out into air:

A

When light enters the glass block, it slows down, this is because glass is more dense than air. The wavelength of the light ray decreases and the direction of the wave moves towards the normal. As the ray moves out of the glass block into air it speeds up, this is because air is less dense than glass. The wavelength of the light ray increases and the direction moves away from the normal line.

33
Q

Describe the investigation in order to investigate refraction of light:

A

1) Place the glass block in the centre of the piece of paper and draw around the perimeter of the box
2) remove the block and draw a dotted normal line perpendicular to the edge of the long side of the block, roughly half way along
3) Draw a line to represent the incident ray 30* to the normal
4) Place the glass block back within the rectangle you have drawn
5) Switch on the ray box with a narrow slit in front of the light bulb and shine the ray along the incident ray you have drawn
6) Observe the path of the light through the block and out the other side
7) Mark the path of the emergent light ray on the other side
8) Remove the glass block. Draw a normal at the point where the light emerged from the glass block.
9) Draw a line to join the incident ray and emergent ray through the rectangle representing the glass block to give the refracted ray
10) Measure the incident and refracted angles
11) Repeat experiment with a range of angles for the incident ray
12) Repeat experiment and find mean average for each result

*Possible inaccuracies:
The width of the light ray may make it difficult to draw along the centre of the line

34
Q

Explain what happens if white light is shone through a prism

A

White light is made from all the colours of the colour spectrum. As different colours have a different frequency and a different wavelength, they travel at different speeds through the glass of the prism, so they get refracted at different amounts, which allows the prism to split white light into the spectrum

35
Q

What is the wavelength and frequency of Violet light (closest to ultraviolet and x rays)

A

short wavelength, high frequency

36
Q

What is the wavelength and frequency of red light (closest to infrared and microwaves)

A

long wavelength, low frequency

37
Q

Why are some lights different colours?

A

Light is a type of electromagnetic wave. The only difference between the different colours of light are the wavelength / frequency of the electromagnetic wave

38
Q

What is said to happen when white light splits up into separate colours?

A

White light has been dispersed

39
Q

What light is refracted the most?

A

Violet (short wavelength, high frequency)

40
Q

What light is refracted the least?

A

Red light (long wavelength, low frequency)

41
Q

How do colour filters work?

A

They absorb certain wavelengths and transmit other wavelengths

42
Q

What will happen as white light travels towards a blue filter?

A

A blue filter will transmit blue light and absorb all other wavelengths of light

43
Q

What will happen if red light travels towards a green filter?

A

The red light would be absorbed, allowing no light to be transmitted

44
Q

What determines a materials colour?

A

chemicals known as pigments, pigments absorb certain wavelengths of light and strongly reflect others. (for example a red surface contains red pigment, it reflects red light and absorbs all other wavelengths of light)

45
Q

What pigments does a white surface contain?

A

A white surface has no pigments, therefore it reflects any light

46
Q

Why would an object appear black?

A

If it absorbs all wavelengths of light

47
Q

What colour would a blue object appear through a red filter?

A

A blue object viewed through a red filter would appear black. This is because blue objects can only reflect blue light, but the red filter only transmits red light. Therefore, all the light that passes through the filter would be absorbed, causing the object to appear black

48
Q

What colour would a white object appear through a green filter?

A

The white object viewed through a green filter would appear green. This is because white objects reflect all wavelengths of light, and because the filter only transmits green light, only the green light would be reflected by the object. As a result the object would appear green.

49
Q

How can a convex lens be represented?

A
50
Q

How can a concave lens be represented?

A
51
Q

What are the units for mangification?

A

Magnification does not have units as it is a ratio

52
Q

Is the image formed by a magnifying glass real or virtual (when the magnifying glass is used correctly)?

A

Virtual, this is because only the person using the magnifying glass can see the image. The image cannot be projected onto a screen

53
Q

How does a magnifying glass work?

A

A magnifying glass is a convex lens used to make an object appear much larger than it actually is. This works when the object is placed at a distance less than the focal length from the lens.

54
Q

How do you draw a ray diagram for a convex lens?

A

1) Draw a ray passing from the object through the optical centre of the lens
2) Draw a ray which is parallel to the principal axis, which refracts through the lens and passes through the principal focus
3) Draw a ray which passes through the principal focus (on the same side as the object) and is then refracted through the lens, emerging parallel to the principal axis
4) The point at which the lines cross is where the image is formed

55
Q

How do you draw a ray diagram for a concave lens?

A

1) Draw a ray that passes from the object through the optical centre of the lens
2) Draw a ray which is parallel to the principal axis, which refracts through the lens and refracts away from the principal axis (It should refract so that if the ray was continued backwards, it would pass through the principal focus)
3) The point where the rays cross is where the image is formed

56
Q

Label this image:

A 
green = principal axis
purple = optical centre
red = principal focus
blue = focal length
57
Q

Label this image:

A 
Red = Principal axis
Blue = virtual focus
Green = Optical centre
purple = focal length
58
Q

Describe the nature of the image formed from a convex lens when the object is at infinity

A

The image is formed at f, the image is real, the image is inverted, the image is diminished

59
Q

Describe the nature of the image formed from a convex lens when the object is beyond 2f

A

The image is formed between f and 2f, the image is real, the image is inverted, the image is diminished

60
Q

Describe the nature of the image formed from a convex lens when the object is at 2f

A

The image is formed at 2f, the image is real, the image is inverted, the image is the same size

61
Q

Describe the nature of the image formed from a convex lens when the object is between f and 2f

A

The image is formed beyond 2f, the image is real, the image is inverted, the image is magnified

62
Q

Describe the nature of the image formed from a convex lens when the object is at f

A

As the rays are parallel, they never converge, therefore no image is formed

63
Q

Describe the nature of the image formed from a convex lens when the object is closer to the lens that f

A

The image is virtual, the image is upright, the image is magnified

64
Q

Describe the nature of the image formed from a concave lens

A

The image is formed closer the lens than f (and the object), the image is virtual, the image is upright, the image is diminished

65
Q

Draw the ray diagram for a convex lens when the object is at infinity

A
66
Q

Draw the ray diagram for a convex lens when the object is beyond 2f

A
67
Q

Draw the ray diagram for a convex lens when the object is at 2f

A
68
Q

Draw the ray diagram for a convex lens when the object is between f and 2f

A
69
Q

Draw the ray diagram for a convex lens when the object is at f

A
70
Q

Draw the ray diagram for a convex lens when the object is closer to the lens than f

A
71
Q

Draw the ray diagram for a concave lens

A
72
Q

Describe the image formed by a plane mirror

A

The image is virtual, upright, the same size as the object, and the same distance behind the mirror as the object is infront

73
Q

Draw the ray diagram for the image formed on a plane mirror:

A
74
Q

What 3 things may occur when a wave arrives at a boundary?

A
  • The wave may be absorbed by the material the wave is trying to cross into - this transfers energy to the materials energy stores
  • The wave may be transmitted - the waves carry on travelling through the new material. This often leads to refraction
  • The wave is reflected
75
Q

How does a camera work?

A

A convex lens is used to produce a real image of an object on a film (or an array of pixels for a digital camera). The position of the lens is adjusted to focus the image on the film

X GCSE Physics - outdated and incomplete due to advanced information 2022 (12 decks)

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