Chapter 11 Flashcards
(76 cards)
1
Q
what is light?
A
electromagnetic radiation that can be detected by the human eye, an electromagnetic wave that travels extremely fast and in a straight line, and does not require a medium; travels through the vacuum of outer space
2
Q
what is a wave?
A
- a disturbance that transfers energy from one point to another without transferring matter
3
Q
crest
A
highest point of the wave
4
Q
trough
A
the lowest point of the wave
5
Q
rest position
A
the level when there is no wave
6
Q
wavelength
A
the distance from one place in the wave to a similar place in the wave (symbol is lambda: λ)
7
Q
amplitude
A
the wave height from the point of rest to the crest or trough, the larger the amplitude the more energy carried in the wave
8
Q
frequency
A
the rate of repetition of a wave (symbol for frequency is f, measured in hertz Hz)
9
Q
mathematical relationship within waves
A
speed = frequency x wavelength
v = f x λ
10
Q
C = speed of light (in a vacuum)
for white light
A
C = 3.00 x 10^8 m/s
11
Q
medium
A
any physical substance through which energy can be transferred
12
Q
radiation
A
a method of energy transfer that does not require a medium; the energy travels at the speed of light
13
Q
electromagnetic waves
A
a wave that has both electric and magnetic parts, does not require a medium, and travels at the speed of light
14
Q
visible light
A
electromagnetic waves that the human eye can detect
15
Q
electromagnetic spectrum
A
- the classification of electromagnetic waves by energy
- lowest to highest energy
- longest to shortest wavelength
- radio waves, microwaves, infrared light, visible light, ultraviolet light, X-rays, and gamma rays
16
Q
radio waves uses
A
- AM/FM radio
- TV signals
- cellphone communication
- radar
- astronomy (ie/ discovery of pulsars)
17
Q
microwaves uses
A
- telecommunications
- microwave ovens
- astronomy (ie/ background radiation associated with the big bang)
18
Q
infrared light uses
A
- remote controls (ie/ DVD players and game controllers)
- lasers
- heat detection (ie/ leakage from windows, roofs) and remote sensing
- keeps food warm (in fast food restaurants)
- astronomy (ie/ discovering the chemical composition of celestial bodies)
- physical therapy
19
Q
visible light uses
A
- human vision
- theatre/concert lighting
- rainbows
- visible lasers
- astronomy (ie/ optical telescopes, discovering the chemical composition of celestial bodies)
20
Q
ultraviolet light uses
A
- causes skin to tan and sunburn
- increases risk of developing skin cancer
- stimulates production of vitamin D
- kills bacteria in food and water (sterilization)
- “black” lights
- ultraviolet lasers
- astronomy (ie/ discovering the chemical composition of celestial bodies)
21
Q
X-rays uses
A
- medical imaging (ie/ of teeth and broken bones)
- security equipment (ie/ scanning of luggage at airports)
- cancer treatment
- astronomy (ie/ study of binary star systems, black holes, the centre of galaxies)
22
Q
gamma rays uses
A
- cancer treatment
- astronomy (ie/ study of nuclear processes in the universe)
- product of some nuclear decay
23
Q
visible specutrum
A
the continuous sequence of colours that make up white light: ROYGBIV (in increasing every order)
24
Q
luminous
A
- produces its own light
- such as a fire, the sun, firefly
25
non-luminous
- does not produce its own light
- such as a desk, rock, or stick
26
incandescence
the production of light as a result of high temperature
27
electric discharge
the process of producing light by passing an electric current through a gas
28
phosphorescence
the process of producing light by the absorption of ultraviolet light, resulting in the emission of visible light over an extended period of time (glow-in-the-dark stars)
29
fluorescence
the immediate emission of visible light as a result of the absorption of ultraviolet light
30
chemiluminescence
the direct production of light as the result of a chemical reaction with little or no heat produced (glow sticks), known as “cold light”
31
bioluminescence
the production of light in living organisms as the result of a chemical reaction with little or no heat produced (fireflies), often to protect themselves
32
triboluminescence
the production of light from friction qs a result of scratching, crushing, or rubbing certain crystals
33
light-emitting diode (LED)
light produced as a result of an electric current flowing in semiconductors, does not require a filament, does not produce as much heat, and is more energy efficient
34
semiconductor
a material that allows an electric current to flow in only one direction
35
fluorescent light
in a fluorescent light, electricity causes the mercury vapour to emit ultraviolet light; this ultraviolet light hits the fluorescent material on the inner surface of the light tube, causing visible light to be emitted
36
what is a laser?
- Light Amplification by Stimulated Emission of Radiation
- a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation
- very pure in colour, intense, and concentrated into one narrow beam
- waves travel in exactly the same direction and are exactly in unison
37
light ray
a line on a diagram representing the direction and path that light is travelling
38
geometric optics
the use of light rays to determine how light behaves when it strikes objects
39
incident light
light emitted from a source that strikes an object
40
transparent
when a material transmits all or almost all incident light; objects can be clearly seen through the material
41
translucent
when a material transmits some incident light but absorbs or reflects the rest; objects are not clearly seen through the material
42
opaque
when a material does not transmit any incident light; all incident light is either absorbed or reflected; objects behind the material cannot be seen at all
43
image
reproduction of an original object produced through the use of light
44
mirror
any polished surface reflecting an image/that exhibits reflection; most mirrors consist of two parts - the front is a sheet of glass and the back is a thin layer of reflective silver or aluminum foil
45
reflection
the bouncing back of light from a surface
46
plane mirror
a flat mirror that illustrates how predictable the path of light is when it hits the mirror
47
incident ray
the incoming ray that strikes a surface (IR)
48
reflected ray
the ray that bounces off a reflective surface (rR)
49
normal
the perpendicular line to a mirror surface, an imaginary line
50
angle of incidence
the angle between the incident ray and the normal
51
angle of reflection
the angle between the reflected ray and the mirror
52
laws of reflection
1) the angle of incidence equals the angle of reflection
2) the incident ray, reflected ray, and the normal all lie on the same plane
53
specular reflection
reflection of light off a smooth surface, where parallel rays all bounce off at the same angle
54
diffuse reflection
reflection of light off an irregular or dull surface, causes reflected rays to travel in different directions
55
virtual image
an image formed by light coming from an apparent light source; light is not arriving at or coming from the actual image location. the light rays never converge
56
characteristics of a plane mirror
1) the image appears to be located the same distance behind the mirror as the object is in front of the mirror
2) the object-imagine line is perpendicular to the mirror surface
57
SALT
1) size
2) altitude
3) location
4) type
58
real image
an image formed when light is actually arriving at the image location, it can be reflected on a screen, and light rays converge
59
concave (converging) mirror
a mirror shaped like part of the surface of a sphere in which the inner surface is reflected
60
convex (diverging) mirror
a mirror shaped like part of the surface of a sphere in which the outer surface is reflective
61
centre of curvature
the centre of the sphere whose surface has been used used to make the mirror
62
principal axis
the line through the centre of curvature to the midpoint of the mirror
63
vertex
the point where the principal axis meets the mirror and bisects it
64
converge
to meet at a common point
65
focus
the point at which light rays parallel to the principal axis converge when they are reflected off a concave mirror, half of the centre of curvature
66
image rules for a concave mirror
1) a light ray parallel to the principal axis is reflected through the focus
2) a light ray through the centre of curvature is reflected back into itself
3) a ray through F will reflect parallel to the principal axis
4) a ray aimed at the vertex will follow the law of reflection (θi=θr)
67
diverge
to spread apart
68
electromagnetic radiation
wave pattern made of electric and magnetic fields that oscillate and can travel through empty space
69
wave model
similarities between light and movement of waves on surface used as a representation of explanation for properties of light
70
OLED
a light emitting diode in which the emissive electroluminescent layer is a film of organic compound that emits light in response to an electric current
71
plasma
created by adding energy to a gas so that some of its electrons leave their atoms. this is ionization. it results in negatively charged electrons, and positively charged ions
72
LCD
a flat panel display or other electronically modulated optical device that uses the light modulating properties of liquid crystals combined with polarizers
73
propagation
direction of wave travel
74
transverse wave
a wave in which the medium vibrates at right angles to the direction of its propagation
75
umbra
the fully shaded inner region of a shadow cast by an opaque object
76
penumbra
a region of lighter shadow around the darkest part of a shadow
