Unit 1 Flashcards
(60 cards)
1
Q
Describe Red Shift
A
- galaxies moving away
- wavelength increases
- frequency decreases
- more distant, bigger shift
2
Q
What does step up transformer do?
A
- increase voltage
- decrease current
- decrease energy loss
- increase efficiency
3
Q
How does standby damage environment?
A
- electricity needs to be generated
- power stations needed
- fossil fuels burnt -> greenhouse gases -> global warming
4
Q
Pros of nuclear power (8)
A
- no greenhouse gases
- high energy density in fuel
- longer operating life
- reliable
- small volume of waste
- buy less fuel from other countries
- concentrated source of energy
- fossil fuels last longer (conserves fossil fuels)
5
Q
Pros of wind energy (6)
A
- no greenhouse gases
- small plot of land, still used for farming
- low running costs
- renewable
- energy source (wind) free
- conserves fossil fuels
6
Q
Cons of wind energy (8)
A
- kills birds
- noise
- eyesore
- unreliable cuz weather dependent
- dilute energy source
- large initial cost
- times when not enough electricity generated
- co2 used in manufacture
7
Q
What is a digital signal
A
signal that has two states
8
Q
What is an analogue signal
A
signal caries continuously
9
Q
What is the big bang?
A
- universe expanding
- after explosion at one pint
10
Q
Pro of sending info as digital not analogue
A
- less interference
- signal restored
- easily accessible by computer
11
Q
Con of fossil fuels
A
- release co2
- leads to global warming
12
Q
Properties of EM waves
A
- travel through vacuum
- at same speeds
- can be reflected
- can be refracted
13
Q
What happens to wasted energy?
A
- transferred to surroundings as heat
- not usually transformed
- spreads out and diff to use usefully for further energy transformations
14
Q
What is specific heat capacity?
A
amount of energy required to change the temperature of one kilogram of the substance by 1 degree Celsius
15
Q
Why devices on standby damage environment/ why reducing energy reduces co2 emitted in a (converse)
A
- ff burnt - global conserves, less greenhouse
- uses electricity which needs to be generated
- power stations needed
16
Q
What is energy efficient?
A
- smaller proportion of energy supplied is wasted
- most energy usefully transformed
17
Q
How does the design of a black stove/radiator improve rate of energy transfer?
A
- black is good emitter of infrared
- give max energy transfer
- matt better emitters
- large sa
18
Q
Why temp fall fastest just after switches off/water cooled faster first 5 mins (converse for what happens to energy transfer with heater when switched off) (2)
A
- bigger energy diff between water and surrounding air
- so transfer of energy is faster
19
Q
Why fins affect rate of energy transfer (converse small ears help in cold)(2)
A
- Fins increase SA/decrease
- so rate of energy transfer/evaporation increases/decreases
20
Q
How is heat transferred by convection from bottom to top of oven?
A
- particles gain energy
- move faster
- move apart
- air expands
- less dense
- hot air rises
21
Q
Why (this) light and shiny?
A
- less heat loss
- poor emitters of radiation
22
Q
Why is the fridge light and shiny?
A
- poor absorber of heat
- good reflector of heat
- reduces heat transfer into fridge
23
Q
Why does the energy supplied equal the energy transferred?
A
energy cannot be destroyed
24
Q
Does the fridge or the freezer have the greatest rate of energy transfer?
A
- freezer
- greater temp diff between freezer and room
25
Electric motor transfers electrical energy to...
kinetic
26
Explain conduction through metals
- metals have free electrons
- kinetic energy of electrons increase (gain ke)
- electrons move faster
- electrons transfer energy by colliding with other electrons and ions
27
How does the vacuum flask keep the liquid hot? (8)
- PLASTIC poor conductor so stops CONDUCTION
- stops CONVECTION currents from forming on top of flask so stopping energy transfer by CONVECTION
- Particles evaporating from it cannot move into air, stopping evaporation
- GLASS poor conductor so removes energy transfer by CONDUCTION
- VACUUM between walls: both conduction and convection require particles so stops energy transfer between 2 walls by CONDUCTION AND CONVECTION
- SILVERED SURFACE reflects infrared RADIATION back
- poor emitters of infrared
- reduces radiation
28
What effect does energy transferred have on the environment?
warms it
29
Why do solids have a fixed shape and are difficult to compress? (6)
- particles closer together
- so no room for them to move closer (hard to compress)
- vibrate about fixed point
- strong forces of attraction (at a distance)
- forces become repulsive is particles get closer
- particles strongly held together/not free to move around (shape is fixed)
30
Why do gases fill the container and are easy to compress? (5)
- particles far apart
- negligible forces of attraction
- space between particles (easy to compress)
- move randomly
- spread out in all directions (to fill the container)
31
How does plastic foam reduce energy transfer by convection?
- air trapped, good insulator
| - air cannot form convection current
32
Why ovens shiny/foil?
- good reflector
- outside bad emitter
- increase energy reaches biscuit
33
Electricity that is not provided through the national grid is more efficient. Why?
- less energy loss
| - cuz shorter cables
34
Why xrays not used for space satellites?
cannot pass through atmosphere
35
Con of UV
causes skin cancer
36
Evidence proves Big Bang
CMBR
37
Pro of gas
- short start up time
- meet surges in demand
- fewest emission of gg from the fossil fuels
38
Which wave has shortest wavelength/ highest frequency?
gamma
39
Which wave has longest wavelength/ lowest frequency?
radio
40
Why are microwaves used for satellites?
can pass through ionosphere
41
When does diffraction occur?
when wavelength similar size to size of gap
42
Pro of hydroelectricity
can store energy for later use
43
What is virtual image?
image formed from intersection of virtual rays
| cannot be projected onto a screen
44
What is decommissioning?
dismantle and remove radioactive waste
45
Pro of underground cables
- cannot be seen
- not damaged by weather
- no hazard to aircraft
46
Carbon capture
not released but stored
47
What is nuclear fission?
process of nuclear fuel providing energy to generate electricity in nuclear power station by the splitting of nuclei
48
What does increased the amplitude do?
increase loudness
49
Trend of frequency and wavelength
frequency increases, wavelength decreases
50
What is u value?
how effective a material is as an insulator
51
how is the u value affected by increasing the amount of insulation?
decreases
52
Why line graph?
continuous data
53
Properties of all EM waves
- transverse
- same speed (through air)
- can be absorbed
- can be reflected
- can be refracted
- can be diffracted
- can transfer energy
- can travel through vacuum
54
Describe how heated water used to generate electricity in solar thermal power station
- hot water turns to steam
- steam turns turbine
- turbine turns generator
55
Why must molten chemical salts have a high specific heat capacity?
so they can store large amount of energy
56
Why doesn't solar storage power station not operate at maximum possible electrical output every day of year?
- number of daylight hours varies
| - mean power received from sun per square meter varies
57
unit for specific heat capacity
J/kg degree C
58
Describe the Doppler effect
-when source moves relative to observer
-there is change in frequency and wavelength
-if source moves away from: wl increase, f decrease
-if source moves towards: wl decrease, f increase
(SAME SPEED)
59
Energy transfer by convection
- particles spread out
- air becomes less dense (expands)
- so warm air rises
60
2 features to help metal cooling fins transfer energy quickly to surroundings
- large sa
| - black/dark colour
