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Physics > Unit 1 > Flashcards

Unit 1 Flashcards

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1
Q

Describe Red Shift

A
  • galaxies moving away
  • wavelength increases
  • frequency decreases
  • more distant, bigger shift
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2
Q

What does step up transformer do?

A
  • increase voltage
  • decrease current
  • decrease energy loss
  • increase efficiency
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3
Q

How does standby damage environment?

A
  • electricity needs to be generated
  • power stations needed
  • fossil fuels burnt -> greenhouse gases -> global warming
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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)
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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
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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
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7
Q

What is a digital signal

A

signal that has two states

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8
Q

What is an analogue signal

A

signal caries continuously

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9
Q

What is the big bang?

A
  • universe expanding

- after explosion at one pint

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10
Q

Pro of sending info as digital not analogue

A
  • less interference
  • signal restored
  • easily accessible by computer
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11
Q

Con of fossil fuels

A
  • release co2

- leads to global warming

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12
Q

Properties of EM waves

A
  • travel through vacuum
  • at same speeds
  • can be reflected
  • can be refracted
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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
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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

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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
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16
Q

What is energy efficient?

A
  • smaller proportion of energy supplied is wasted

- most energy usefully transformed

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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
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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

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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

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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
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21
Q

Why (this) light and shiny?

A
  • less heat loss

- poor emitters of radiation

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22
Q

Why is the fridge light and shiny?

A
  • poor absorber of heat
  • good reflector of heat
  • reduces heat transfer into fridge
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23
Q

Why does the energy supplied equal the energy transferred?

A

energy cannot be destroyed

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24
Q

Does the fridge or the freezer have the greatest rate of energy transfer?

A
  • freezer

- greater temp diff between freezer and room

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25
Q

Electric motor transfers electrical energy to…

A

kinetic

26
Q

Explain conduction through metals

A
  • 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
Q

How does the vacuum flask keep the liquid hot? (8)

A
  • 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
Q

What effect does energy transferred have on the environment?

A

warms it

29
Q

Why do solids have a fixed shape and are difficult to compress? (6)

A
  • 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
Q

Why do gases fill the container and are easy to compress? (5)

A
  • 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
Q

How does plastic foam reduce energy transfer by convection?

A
  • air trapped, good insulator

- air cannot form convection current

32
Q

Why ovens shiny/foil?

A
  • good reflector
  • outside bad emitter
  • increase energy reaches biscuit
33
Q

Electricity that is not provided through the national grid is more efficient. Why?

A
  • less energy loss

- cuz shorter cables

34
Q

Why xrays not used for space satellites?

A

cannot pass through atmosphere

35
Q

Con of UV

A

causes skin cancer

36
Q

Evidence proves Big Bang

A

CMBR

37
Q

Pro of gas

A
  • short start up time
  • meet surges in demand
  • fewest emission of gg from the fossil fuels
38
Q

Which wave has shortest wavelength/ highest frequency?

A

gamma

39
Q

Which wave has longest wavelength/ lowest frequency?

A

radio

40
Q

Why are microwaves used for satellites?

A

can pass through ionosphere

41
Q

When does diffraction occur?

A

when wavelength similar size to size of gap

42
Q

Pro of hydroelectricity

A

can store energy for later use

43
Q

What is virtual image?

A

image formed from intersection of virtual rays

cannot be projected onto a screen

44
Q

What is decommissioning?

A

dismantle and remove radioactive waste

45
Q

Pro of underground cables

A
  • cannot be seen
  • not damaged by weather
  • no hazard to aircraft
46
Q

Carbon capture

A

not released but stored

47
Q

What is nuclear fission?

A

process of nuclear fuel providing energy to generate electricity in nuclear power station by the splitting of nuclei

48
Q

What does increased the amplitude do?

A

increase loudness

49
Q

Trend of frequency and wavelength

A

frequency increases, wavelength decreases

50
Q

What is u value?

A

how effective a material is as an insulator

51
Q

how is the u value affected by increasing the amount of insulation?

A

decreases

52
Q

Why line graph?

A

continuous data

53
Q

Properties of all EM waves

A
  • 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
Q

Describe how heated water used to generate electricity in solar thermal power station

A
  • hot water turns to steam
  • steam turns turbine
  • turbine turns generator
55
Q

Why must molten chemical salts have a high specific heat capacity?

A

so they can store large amount of energy

56
Q

Why doesn’t solar storage power station not operate at maximum possible electrical output every day of year?

A
  • number of daylight hours varies

- mean power received from sun per square meter varies

57
Q

unit for specific heat capacity

A

J/kg degree C

58
Q

Describe the Doppler effect

A

-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
Q

Energy transfer by convection

A
  • particles spread out
  • air becomes less dense (expands)
  • so warm air rises
60
Q

2 features to help metal cooling fins transfer energy quickly to surroundings

A
  • large sa

- black/dark colour

Physics (3 decks)

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