P14 Flashcards

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1
Q

What can all waves be?

A

Absorbed,transmitted or reflected

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2
Q

When a wave arrives at a boundary between two different materials what happens?

A
  • The waves are absorbed by the material the wave is trying to cross into this transferes the energy to the material energy stores
  • The waves are transmitted. Refraction happens
  • The waves are reflected
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3
Q

Angle of incidence =

A

Angle of reflection

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4
Q

Whats the angle of incidence?

A

The angle between the incoming line and normal

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5
Q

Whats the angle of reflection?

A

The angle between the reflected and the normal

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6
Q

Whats the normal line?

A

An imaginary line perpindicular to the surface at the point of incidence. Normally the dotted line

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7
Q

When does specular reflection happen?

A

A wave is reflected in a single direction by a smooth surface.

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8
Q

Give an example of specular reflection?

A

When light is reflected in the mirror and you get a clear reflection

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9
Q

What is diffuse reflection?

A

When a wave is reflected by a rough surface and the rays are scattered in different directions

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10
Q

What happenes when loght is reflected by a rough surface?

A

The surface appears matte and you don’t get a clear reflection of objects

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11
Q

What’s refraction?

A

Waves changing direction at a boundary

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12
Q

What happens when a wave crosses a boundary at an angle and changes direction?

A

It refracts

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13
Q

What does how much it refracts depend on?

A
  • How much it speeds up or slows down
  • Also density of 2 materials
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14
Q

What does a higher density mean?

A

It will slow down

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15
Q

What happens when a wave crosses a boundary and slows down?

A

It will bend towards the normal line

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16
Q

What happens if it crosses into another material and speeds up?

A

Bend away from the normal line

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17
Q

What happens when the wavelength of a wave stays the same?

A

The frequency stays the same

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18
Q

What happens if a wave travels across the normal line?

A

Change speed but not refract

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19
Q

Why do waves go in a different direction?

A

The wave hit a medium

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20
Q

Whats the optical density?

A

A measure of How quickly light can travel through it

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21
Q

What does higher the optical density mean?

A

The slower light waves travel through it

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22
Q

Why should you do the practical in a dim room?

A

So you can see the light rays better

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23
Q

What materials can you use to investigate refraction?

A

Transparent

24
Q

What are the steps for the transparent material?

A

1) Place a transparent block on a peice of paper and trace around it. And shine a ray box at the block
2) trace the incident ray and mark the emerging ray. Then draw a straight line to each other to show the refracted ray
3) draw the normal when the light enetered the block, use a protractor to measure between the normal and refracted.
4) Repeat using rectangle blocks with different materials keeping the incident ray the same.

Angle of refraction change for different materials

25
Q

How do lenses form images?

A

By refracting light and chnaging it’s direction

26
Q

Whats a convex lens?

A

Bulges outwards and causes rays of light parallel to the axis to be brought together at the focus point.

27
Q

Whats a concave lens?

A

Caves inwards and causes parallel rays of light to spread out

28
Q

Whats the axis of a lens?

A

The line passing through the middle of the lens

29
Q

Whats the principle focus of a convex lens?

A

Is where rays hitting the lens parallel to the axis all meet

30
Q

Whats the principle focus of a concave lens?

A

The point where rays hitting the lens parallel to the axis appear to all come from.

31
Q

Whats the focal length?

A

The distance from the centre of the lens to principle focus

32
Q

What are the 3 rules for refraction in convex lens?

A
  • an incident ray parallel to the axis refracts through the lens and passes through the principal focus on the other side.
  • an incident ray passing through the principal focus refracts through the lens and travels parallel to the axis
  • an incident ray passing through the centre carrys on
33
Q

Rules for concave lens?

A
  • An incident ray passing through the centre of the lens carrys on in same direction
  • An incident ray passing towards the principal focus refracts through the lens and is parallel to the axis
  • An incident ray parallel to the axis refracts through the lens and travels in line with the prinicpal focus
34
Q

What can lenses produce?

A

Real and virtual images

35
Q

What is a real image?

A

When the light from an object comes together to form an image on the screen like the image formed on the eyes retina

36
Q

Whats a virtual image?

A

Is when rays are diverging so the light from the object appears to come from a different place

37
Q

An example of a virtual image?

A

When you look in the mirror because the objects behind the mirror

38
Q

What are the 3 things to describe an image?

A
  • How big is it
  • Real or virtual
  • Upright or inverted
39
Q

What lens always creates virtual images?

A

Concave lens

40
Q

What uses convex lenses?

A

Magnifying glasses

41
Q

Magnification =

A

Image height/object height

42
Q

What is visible light made from?

A

A range of colours

43
Q

What does each colour have?

A

Own range of wavelengths and frequencies

44
Q

How do you make other colours?

A

By mixing them

45
Q

What are the ony colours you can get without mixing?

A

Red,green,blue

46
Q

What do all different colours create?

A

White light

47
Q

What do colour and transparency depend on?

A

Absorbed wavelengths

48
Q

What happens when visible light hits an opaque objects?

A

They absorb some wavelength and reflect others

49
Q

What does the colour of an opaque object depend on?

A

Which wavelengths are strongly reflected

50
Q

What happens to opaque object that aren’t a primary colour?

A

They reflect on other wavelengths of light corrosponding to that colour

51
Q

What do white objects reflect.

A

All visible light equally

52
Q

What do black objects absorb?

A

All wavelengths of visible light

53
Q

What are colour filters used for?

A

Filter out different wavelenths of light so that only certain colours are transmitted

54
Q

What does a primary colour transmit?

A

Only that colour

55
Q

What happens when a different colour goes through a colour filter ?

A

Goes black