1The law of reflection.
the angle of incidence is equal to the angle of reflection
2The normal is drawn at
90 degrees to the surface
3When light goes from a more dense to a less dense medium
Light bends away from the normal
4When light goes from a LESS dense medium to a MORE dense medium
light bends towards the normal
5Refraction occurs because
When light passes a boundary the rays of light change direction because the light changes speed
6During refraction, what happens to the frequency
It does not change
7When the angle of refraction is exactly 90 degrees
The light is refracted along the boundary The angle of incidence is the critical angle
8Total internal reflection occurs when
The angle of incidence is greater than the critical angle and the incident material is denser than the second material
9Specular reflection is defined as
Reflection from a smooth surface in a single direction
10Diffuse reflection is
Reflection from a rough surface causing scattering
11The colour that is transmitted is the
Same colour as the filter
12The smaller the wavelength
The greater the refraction
13The two types of lenses are
converging, diverging
14What is the point in a converging lens where parallel light rays are brought to a Focus
Principal focus
15The distance from lens to principal focus is the
Focal length
16The focal length depends on
How curved the lens is
17In a diverging lens, parallel rays of light
Diverge from a point
18Where is fhe principal focus on a diverging lens
The point from which the rays appear to diverge
19A real image is defined as
An image that is formed when the light rays from an object converge and meet each other and can be projected on a screen
20A real image is always
inverted and formed in front of the lens
21Real images are where two
Solid lines cross in ray diagrams
22A virtual image is defined as
An image that is formed when the light rays from an object do not meet but appear to meet behind the lens and cannot be projected onto a screen
23Can virtual images be projected on a screen?
Nope
24Virtual images are where on a ray diagram
Two dashed lines or one dashed and one solid line meet
25Using a converging lens, if the object is placed between f and 2f then a
Real, inverted, magnified image is formed
26Using a converging lens, if the object is placed beyond 2f, then a
Real, inverted, diminished image is formed
27Note - practice drawing ray diagrams with pencil and paper
Not on quizlet
28Using a convex lens, if the object is placed closer to the lens than the focal length, then
A magnified, upright virtual image is formed behind the object
29If a concave lens is used, then the image will
Always be virtual
30If the object is in front of the concave lens
A diminished, upright, virtual image is formed
31Electromagnetic waves are
Transverse waves that transfer energy from the source to an absorber
32Three main properties of em waves
They are all transverse
Travel through a vacuum
Travel same speed in vacuum
33List the 7 types of EM waves from low to high frequency
Radio wave
Microwave
Infrared
Visible light (red to violet)
Ultraviolet
X ray
Gamma rays
34As the frequency increases, the energy
increases
35All objects emit
infrared radiation
36Radiation with high energy is
Highly ionising
Harmful to cells and tissues causing cancer
37Visible light is defined as
The range of wavelengths which are visible to humans
38Visible light has a wavelength range of
400-740 nanometers
39Dispersion
Different wavelengths of light slow by different amounts. This effect is seen with visible light when it passes through a prism and separates into its constituent colours - a spectrum is formed
40Which colour of visible light is refracted most/ least
Violet is refracted most
Red is refracted least
41What makes an EM wave more dangerous
Increase frequency
Increase intensity
43Microwave danger
Internal heating of body organs
44Infrared dangers
Skin burns
45Visible light dangers
Bright light causes eye damage
46UV rays danger
Eye damage
UV is ionising so can kill cells, resulting in premature ageing, skin cancer and sunburn
47X ray danger
Kills cells
Mutation
Cancer
49Use of radio waves
Long range communications
Because they can be reflected from earth's atmosphere
50Uses of microwaves
Satellite communications
Because microwaves can penetrate earth's atmosphere
Cooking food
Because water molecules absorb microwaves, heating up the food
51Uses of infrared
Optical fibre communication
Because they can undergo TIR
Remote controls, thermal imageing, night vision, heating cooking, motion sensors, electrical heaters, infrared cameras
52Visible light uses
Seeing and taking photos
Because cameras can detect visible light
Fibre optic comms
53Ultraviolet uses
Detecting security ink
Because it fluoresces with UV lighting
Detecting fake notes
Because they have UV markings
Getting a suntan
Because you want to die from cancer
54X-Rays Uses
To photograph bones
Because x rays penetrate soft tissues but not bones
Other x ray images - ie airport security and industry
55Gamma rays
Sterilise medical equipment because gamma kills bacteria
Treating and detecting cancer - highly ionising
Becoming the hulk - because
56When an EM wave hits an atom it can be absorbed....
By one of the electrons giving it energy. The electron moves up to a higher energy level. Then, the electron moves back down to a lower energy level and emits an EM wave
57How to produce a radio wave and receive
Connect an antenna to a high frequency alternating current
The oscillation of charge in the ac circuit produces radio waves with the same frequency of oscillation
In the receiving antenna, the metal aerial absorbs the radio waves, creating an alternating current with the same frequency as the transmitted wave
58The hotter the object
The more IR radiation emitted in a given time
59As the temperature increases, the peak intensity
Moves to a lower wavelength
60As tenperature increases, the intensity of the emitted radiation
Increase
61At room temp thermal radiation in the form of .... is emitted
IR
62At around 1000 degrees Celsius, objects emit
Red light
63At 6k degrees, object emits
White or blue light
64At even higher temperatures objects emit
UV and X rays
65The temperature of a body increases
When the body absorbs radiation faster than it emits radiation
66Thermal equilibrium
The point where the object reaches a constant temperature where it is absorbing radiation at the same rate as it is emitting radiation
67What kind of surface is best for emitting radiation
Dark, Matt surface
68What kind of surface is worst for emitting radiation
Light, shiny surface
69Greenhouse gases
Absorb and reflect back longer wavelength infrared radiation emitted by earth, preventing it from escaping into space
Eg, CO2, CH4, H2O
70Describe the greenhouse effect
1. The Sun's thermal radiation reaches the Earth's atmosphere where:
Some radiation is reflected back into space
Any radiation not reflected is absorbed and re - radiated by greenhouse gases
2. The absorbed radiation warms the atmosphere and the surface of earth
3. Earth remits at longer wavelengths such as IR
4. Some heat is absorbed by greenhouse gases and re-emitted in all directions, which is trapped in earth's atmosphere , making earth hotter
71Core practical investigating thermal radiation variables and controls
Independant variable - colour
Dependant variable - temperature change
Control - identical flasks (except colour)
Amount of hot water
Same start temp
Same time interval
72Core practical investigating thermal radiation equipment
Kettle - to boil water
4 thermometers - to measure temp of water
Flasks painted black, dull grey, white, silver - to investigate heat loss of different colours
Heatproof May - protect the surface and prevent heat loss from bottom of flask
Stopwatch - record time for water to cool
73Method of core practical thermal radiation
1. Set up the four flasks
2. Fill the flasks with hot water, ensuring the same starting temperature
3. Note starting temp,nyhen measure the temperature at regular intervals
74The intensity and wavelength of emitted radiation depends on
Temperature of body
Surface area of body
Colour of surface