P14 lenses Flashcards

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1
Q

what type of images are always formed from a concave lense

A

virtual

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2
Q

what are the two types of lense

A
  • convex
  • concave
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3
Q

what lense is the one which seperates light rays

A

concave

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4
Q

what are the two types of reflection

A
  • diffuse
  • specular
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5
Q

what is diffuse reflection

A

when light is reflected in all directions from rough surfaces

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6
Q

what is specular reflection

A

when light is refleccted in one direction off of a smooth surface

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7
Q

what should you do to find the prosition of an object with a mirror

A
  • draw a ray from object & reflect
  • draw another ray & reflect
  • extrapolate both rays
  • image is formed where line cross
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8
Q

what are the two types of images

A
  • virtual
  • real
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9
Q

what are the two sizes of images

A
  • magnified
  • diminished
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10
Q

what are the two ways of images

A
  • upright
  • inverted
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11
Q

what are the other names of a convex and concave lense

A
  • converging
  • diverging
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12
Q

what is the focal length

A

the distance from the center of a lens to the point where light rays parallel to the principal axis are focused.

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13
Q

where is the principal focus of a convex image

A

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

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14
Q

where is the principle focus of a concave image

A

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

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15
Q

what are the rules when refraction in a convex lense

A
  • parallel ray goes straight then through focal point
  • central ray goes straight through centre of lense
  • image is formed where the lines cross (real or virtual)
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16
Q

what are the rules when refraction in a concave lense

A
  • parallel ray goes forward to hit lense ~ extreoplate back
  • centeral ray goes through focal point infront of lense
  • image is forced where lines cross
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17
Q

how do you calculate magnification

A

magnification = image height / object height

18
Q

what is the law of reflection

A

angle of incidence = angle of reflection

19
Q

define a real image

A

An image formed by a lens that can be projected on a screen.

20
Q

define 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.

21
Q

describe refraction

A

Refraction is where light changes direction when it enters a new material.

22
Q

why does refraction happen

A

becuase light rays change speed when entering a new material and bend either towards or away from the normal

23
Q

when velocity of a light ray decreases what happens to the wavelength

A

the wavelength decreases

24
Q

describe a translucent object

A

an object that allows light to pass through, but the light is scattered or refracted

25
Q

describe a transparent object

A

object that transmits all the incident light that enters it

26
Q

what are the three primary colours

A

green, red, blue

27
Q

what are the three secondary colours

A

magenta, cyan, yellow

28
Q

what happens when all colours reflect

A

a white light forms

29
Q

what happens when a light enters a filter

A

A filter will only allow that specific colour to be transmitted.
It will absorb all other colours

30
Q

decribe the focal point

A

the point where light rays parallel to the principal axis of a lens are focused (or appear to diverge from)

31
Q

what is the principle axis

A

horizontal line in the middle of a ray diagram

32
Q

what colour has the largest wavelength

A

red

33
Q

what colour has the smallest wavelength

A

violet

34
Q

what does colour and transparency depend on

A

the absorbed wavelengths

35
Q

what are the three things that can happen to light rays when they hit an object

A
  • absorbed
  • trasmitted
  • reflected
36
Q

why are objects opaque

A

because they absorb some of the colours but reflect other colours

37
Q

what colour do red and blue form

A

magenta

38
Q

what colour do blue and green form

A

cyan

39
Q

what colour do green and red form

A

yellow

40
Q

why would an object be black

A

because they absorbe all wavelengths of visible light

41
Q

what do colour filters do

A

they only let particular wavelengths of light through

42
Q

what would a blue object appear as in a red filter

A

black