Core Science Flashcards
(142 cards)
1
Q
What is the geocentric model?
A
It has the earth at the centre
2
Q
Describe the heliocentric model?
A
The sun is at the centre
3
Q
Who put forward the heliocentric model?
A
Copernicus
4
Q
When was the telescope invented?
A
16th Century
5
Q
What do telescopes allow?
A
The naked eye to view things in great detail
6
Q
What did Galileo discover?
A
4 of Jupiters moons
7
Q
What have photographs allowed?
A
For detailed images of space to be produced
8
Q
What is refraction?
A
When light crosses a boundary and changes speed and therefore direction
9
Q
A line at a right angle to the interface is the what?
A
Normal
10
Q
What do convex lenses do?
A
They cause light rays to converge and form an image
11
Q
What is the point called where the image focuses?
A
Focal point
12
Q
What is the distance between the lens and the focal point?
A
The focal length
13
Q
How do refracting telescopes work?
A
A convex lens (the objective lens) creates the image and the eyepiece lens magnifies it
14
Q
As well as refract, waves also do what at a boundary?
A
They are reflected
15
Q
In order for a reflecting telescope to have a large magnification, what do they need to be?
A
Long
16
Q
What are the disadvantages of large lenses?
A
They are very heavy and difficult to make in the correct shape therefore colours can be distorted
17
Q
What does the primary mirror do?
A
Focuses the rays
18
Q
What does the secondary mirror do
A
It reflects the rays to the eye piece lens
19
Q
What do sea waves do when they hit the shore or a cliff?
A
They transfer energy
20
Q
What type of waves oscillate at right angles to the direction of the wave?
A
Transverse
21
Q
What group of waves are all transverse?
A
Electromagnetic
22
Q
Describe the movement of longitudinal waves
A
The move back and forth in the direction of the wave (in compressions and expansions)
23
Q
What is frequency?
A
How many waves pass per second
24
Q
What is frequency measured in?
A
Hertz
25
What is wavelength?
The distance between waves
26
What is wavelength measured in?
Metres
27
What is amplitude?
The heist of the wave from the rest point
28
What is wave speed?
How fast the wave travels
29
What are the two equations for working out wave speed?
Wave speed = Distance/Time
Wave speed = frequency x wavelength
30
What do sea waves do when they hit the shore or a cliff?
They transfer energy
31
What type of waves oscillate at right angles to the direction of the wave?
Transverse
32
What group of waves are all transverse?
Electromagnetic
33
Describe the movement of longitudinal waves
The move back and forth in the direction of the wave (in compressions and expansions)
34
What is frequency?
How many waves pass per second
35
What is frequency measured in?
Hertz
36
What is wavelength?
The distance between waves
37
What is wavelength measured in?
Metres
38
What is amplitude?
The heist of the wave from the rest point
39
What is wave speed?
How fast the wave travels
40
What are the two equations for working out wave speed?
Wave speed = Distance/Time
Wave speed = frequency x wavelength
41
Who discovered infrared?
Herschel
42
Describe Herschel's discovery of infrared?
He noticed that different coloured filters heated up his telescope different amounts so he took the temperatures and noticed that the temperature rose yet again beyond the red light and he therefore called this 'invisible ray' infrared
43
Who discovered ultraviolet?
Ritter
44
Describe the discovery of ultraviolet?
He noticed that silver chloride turned black faster under violet light, he then showed that it turned black fastest beyond the violet and he named it ultraviolet
45
Can EM waves travel through a vacuum?
Yes
46
How fast do EM waves travel?
300,000km per second
47
Name the EM waves from shortest wavelength to the longest?
```
Gamma
X-Ray
Ultraviolet
Visible
Infrared
Microwaves
Radio waves
```
48
Why are microwaves dangerous to humans?
They can heat water which can be dangerous as our bodies are mostly water
49
Why is infrared dangerous for humans?
It's absorbed by skin and causes burns
50
Why is ultraviolet dangerous for humans?
Causes damage to DNA which causes cancer
51
Why're gamma and X-rays dangerous for humans?
They cause mutations in DNA
52
Name a use of fluorescence
It's used to identify counterfeit bank notes and is sometimes used in security lights
53
What are X-ray scanners used for?
To identify items in luggage
54
What is infrared used for?
It is used for thermal imaging where cctv cameras people who emit infrared
55
What are radio waves used for?
Broadcasting and communications
56
What are microwaves used for?
TV signals and wifi and mobile signals
57
What is gamma used for?
Sterilising food and surgical equipment
58
What is ultraviolet used for?
Disinfect water and sewage
59
How is gamma used in diagnosis and treatment of cancer?
It is used in radiotherapy and used in tracers
60
What is infrared used in?
TVs and optical fibres
61
What is ionising radiation?
Radiation that can remove electrons to form ions
62
What is it called when an element emits gamma all the time?
It is said to be radioactive
63
What two other things are ionising that isn't gamma?
Alpha and beta particles
64
What kind of rays do telescopes allow for viewing?
Visible light
65
What invention has allowed for more data to be gathered? (In terms of space)
Photographs
66
What do spectrometers do?
Analyse different wavelengths
67
Why can the Hubble produce clearer images than ground telescopes?
Because light isn't reflected through the atmosphere
68
What's the difference between space probes, landers and rovers?
Space probe - satellite that detects temperature and takes photos and then transmits the data back to earth
Lander - lands on the planet and monitors certain things
Rover - can move around the planet and collect samples
69
What does SETI stand for and what is it?
Search for extra terrestrial intelligence - they are a series of projects that analyse radio waves to find messages from other intelligent life
70
Describe the stages of the life cycle of an average star
Cloud of gas, protostar, average star, red giant, shell of gas, white dwarf, black dwarf
71
What happens when a star becomes a protostar?
The cloud has become more dense and heats up and begins to glow
72
How long is an average star stable for?
10 billion years - until most of the hydrogen is fused
73
Describe what happens when a star becomes a red giant
The star collapses and the outer layer expands
74
What forms the white dwarf?
The remains from the shell of gas
75
What are the differences between average star and giant star after the main sequence?
A giant star becomes a red supergiant and then a supernova as the outer layers are cast outwards
76
What is the requirements of a star to become a black hole?
If the mass after the supernova is 4 times that of the sun, if not it becomes a neutron star (small but very dense)
77
Describe the main points of the Big Bang theory
Tiny point of concentrated energy
13.5 billion years ago
Constant expansion
78
Describe the steady state theory
New matter is constantly made
| Always existed
79
What is cosmic microwave background radiation?
It is believed to be left over energy from Big Bang
80
As an emergency vehicle drives past, the pitch gets lower, what is this called?
The Doppler effect
81
What does pitch depend on and what happens when a sound source moves?
Pitch depends on frequency and wavelength, as the object moves, they are 'stretched'
82
What happens in red shift?
The wavelength of the object is 'stretched' making it appear red
83
What is frequency measured in?
Hertz
84
All sound waves are ____ and travel in a ___
Longitudinal
Medium
85
What is the range that humans can hear?
20-20,000Hz
86
Anything below 20Hz us referred to as what?
Infrasound
87
What animals use infrasound?
Elephants, giraffes and whales
88
Describe 3 uses of infrasound
Tracking animal behaviour
Monitoring volcanoes (as they give out IS)
Detection of meteors and meteorites
89
Anything about 20,000Hz is referred to as what?
Ultrasound
90
What do bats use ultrasound for?
Echolocation
91
What is sonar equipment used for?
Detection of ocean depth and fish
92
What is the gel used for in ultrasound baby scans?
To prevent the waves reflecting off the skin
93
How is an ultrasound image formed?
From the echoes and the time taken
94
What do earthquakes cause the transmission of?
Seismic waves
95
What do seismometers used for?
To detect seismic waves
96
Where is the focus?
The place where the rock moves
97
What is the epicentre?
The place directly above the focus
98
Describe the differences between P and S waves
P - longitudinal, up and down, faster
| S - transverse, side to side
99
How is the rock beneath the Earth's surface investigated?
Through seismic waves and seismometers
100
What happens to the seismic waves when the rock changes?
Some will be reflected and some with refract and will then be detected a certain distance away
101
What is triangulation?
Working out the epicentre from the reading of 3 seismometers
102
Why do tectonic plates move?
Due to convection currents
103
What can sometimes happen if an earthquake happens in the sea?
A tsunami
104
Tsunamis can't be detected through seismometers so what is used instead?
Pressure sensors
105
What is electricity?
A flow of charged particles
106
What is current?
The rate of flowing charge
107
What is voltage?
A measure of energy transferred by the charge
108
What do solar cells do?
They convert solar energy into electrical energy
109
How does hydroelectricity work?
Electricity is generated from falling water in places where water can be trapped in a resovoir
110
What do wind turbines do?
They convert kinetic energy into electric energy through the movement of the turbine
111
How does geothermal energy work?
Heat is transferred from hot underground rocks to water which turns to steam to turn a turbine
112
How does tidal power work?
They generate electricity when turns in a dam turn as the tide flows in and out
113
How does wave power work?
When floating generators move up and down they generate electricity, also waves can force air up pipes which turns a turbine
114
Why are nuclear power stations non renewable?
Because radioactive metals will run out
115
Fossil fuelled power stations contribute to what two things?
Climate change and acid rain
116
Name 3 advantages of non-renewable energy?
There is a good supply at the moment
Cheaper than renewable fuel
Don't depend on weather or tides
117
If you move a wife in a magnetic field, what will flow and what is this called?
Electric current
Electromagnetic induction
118
If a current has formed as a result of EM induction, what is the current?
An induced current
119
Describe 4 ways a current can be incensed
More turns on the coil
Iron core in the coil
Stronger magnets
Moving wire quicker
120
How can the direction of a current be changed?
By changing the direction of wire movement and the direction of the magnetic field
121
What do some bikes have to produce electricity in their lights?
Dynamos
122
The current in a simple Dynamo only travels in one direction so what does that mean it is?
Direct current
123
Describe how an alternating current is induced in a medium sized generator
It is transferred through slip rings and carbons brushes (the slip rings prevent wires from tangling)
124
How do generators in power stations induce current?
They use electromagnets because strong permanent magnets are too expensive
125
What are electromagnets?
They are magnets produced from electricity to create a powerful magnetic field
126
What is the system called that transfers electricity from stations to homes?
The national grid
127
Why is the voltage so high on the national grid?
To prevent heat energy from being lost in the transmission wires and therefore efficiency is improved
128
What voltage do power stations produce and what is this increased to before being sent around the country?
25 KV which is increased to 400 KV
129
What is the role of a step up and step down transformer?
Step up - increases voltage/decreases current
Step down - decreases voltage/increases current
130
Describe how a transformer works
They consist of 2 coils of wire wound to an iron core. The electricity is supplied to the primary coil and obtained by the secondary coil at a different voltage
131
What is the equation that shows the relationship between voltage in a transformer to the number of turns of coil?
Voltage (P) / V (S) = Turns (P) / (S)
132
What is the energy used by an appliance per second?
Power, measured in watts
133
What is the name of the rating given to an appliance and what is it measured in?
A power rating measured in kilowatts
134
By what measure do electric companies charge electricity use?
Kilowatt per hour
135
What is the pricing system used by electricity companies?
Pence per 1 KW
136
What is payback time?
The amount of time it takes to save the money it costed to buy the item
137
What does the most cost-efficient method do?
Saves the most amount of money compared to the cost
138
Name the forms of energy
Thermal, light, electrical, kinetic, sound, chemical potential, nuclear potential, elastic potential, gravitational potential
139
What is a system?
Something in which we are studying changes
140
Describe the law of conservation of energy
It means that energy cannot be destroyed or created
| Input energy = output energy
141
What does a sankey diagram show (energy conversion diagram)
It shows energy transfers
142
What is efficiency?
How good a device is at converting energy into useful forms
