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P1 > Energy Transfer By Heating > Flashcards

Energy Transfer By Heating Flashcards

1
Q

All objects emit…

A

Infrared radiation

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2
Q

How does the temperature of an object affect the rate at which it emits infrared radiation?

A

The higher the temperature of an object the greater the rate at which

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3
Q

What is infrared radiation?

A

Electromagnetic waves between between visible light and microwaves in the electromagnetic spectrum

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4
Q

What is vacuum?

A

A region that doesn’t contain anything, not even gas particles

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5
Q

Can infrared radiation travel through a vacuum?

A

Yes, it travels through space and this is how we get energy from the sum

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6
Q

Does the transfer of energy by infrared radiation involve particles?

A

NO!!

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7
Q

Do all objects emit infrared radiation?

A

Yes

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8
Q

What are good absorbers of infrared radiation?

A

Dark, Matt surfaces

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9
Q

If an object is painted dull black and left in the sun, will it be hotter than the same object painted shiny white?

A

Yes the black surface will be hitter

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10
Q

What are good emitters of infrared radiation?

A

Dark, Matt surfaces

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11
Q

Will an object painted dull black or shiny white transfer energy quickest and therefore cool down quicker?

A

Dull black surfaces

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12
Q

Which kind of surfaces are good reflectors?

A

Light, shiny surfaces

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13
Q

Why are houses in hit countries often painted white?

A

Because it is a poor absorber of infrared radiation

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14
Q

Why are pipes on a fridge usually painted black?

A

They are the best emitters

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15
Q

How can we make substances change between states?

A

Heating or cooling

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16
Q

In a solid…

A

The particles vibrate around fixed position so the solid has a fixed shape

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17
Q

In a liquid…

A

The particles are in contact with each other but can move about at random, so they do sit have a fixed shale and can flow

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18
Q

How is the arrangement of the particles in a liquid different from that of a solid?

A

The particles in a liquid are in contact with each other but are not in fixed positions like in a solid

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19
Q

In a gas…

A

The particles are usually far apart and move at random much faster, so doesn’t have a fixed shape and can flow

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20
Q

Is the density of a gas much more or less than a solid or liquid?

A

Less

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21
Q

How is the arrangement of particles in a gas different from that in a liquid??

A

Particles in a gas are much further apart and move faster than liquid

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22
Q

Where does conduction mainly occur?

A

Solids

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23
Q

Are liquids and gases good or poor conductors?

A

Poor

24
Q

Explain theprocess of conduction

A

If one end of the solid is heated, the particles at the end gain kinetic energy and vibrate more, this energy is passed to neighbouring particles and in this way the energy is passed through the solid

25
Q

Explain conduction in a metal

A

When metals ,s are heated their free electrons gain kinetic energy and move through the metal, transferring energy by colliding with other particles. Metals are good conductors

26
Q

What are poor conductors called?

A

Insulators

27
Q

What materials are good insulators?

A

Wool and fibreglass because they contain trapped air

28
Q

Why are materials that trap air good insulators?

A

Air is s poor conductor so materials with trapped air are good insulators

29
Q

What does convection occur in?

A

Fluids, gases and liquids

30
Q

What is convection?

A

The circulation of a fluid caused by heating it

31
Q

Explain convection

A

When a fluid is heated it expands, the fluid becomes less dense and rises the warm fluid is replaced by cooler, denser fluid. The resulting convection current transfers energy throughout the fluid

32
Q

Why doesn’t convection occur in solids?

A

Because solids have fixed positions and cannot flow

33
Q

Why does a fluid become less dense when heated?

A

Because it expands so there is the same mass of material in a larger volume

34
Q

Where do convection currents occur on a very large scale?

A

Onshore and offshore breezes

35
Q

What is evaporation?

A

When a liquid turns to a gas

36
Q

Why does evaporation occur?

A

Because the most energetic liquid molecules escape from the liquids surface and enter the air

37
Q

Why does evaporation cause cooling?

A

All the energetic liquid molecules leave so the average kinetic energy of the remaining molecules is less so the temperature of the liquid decreases

38
Q

What increases the rate of evaporation?

A

Increasing the surface area of the liquid
Increasing the temp of the liquid
Creating a drought across the liquids surface

39
Q

What is condensation?

A

When a gas turns to a liquid

40
Q

What increases the rate of condensation?

A

Increasing surface temp

Reducing surface temperature

41
Q

The greater the temperature difference between an object and its surroundings…

A

The greater the rate at which energy is transferred

42
Q

What other factors affect rate of energy transfer?

A

The materials the object is in contact with
The objects shape
The objects surface area

43
Q

How can you maximise the rate of energy transfer to keep things cool?

A

Use good conductors
Are painted dull black
Have air flow around them maximised

44
Q

How do we minimise the rate of energy transfer by conduction, convection or radiation to keep things warm?

A

Are good insulators
Are white and shiny
Prevent convection Currents by trapping air in small pockets

45
Q

Why does trapping air in small pockets minimise rate of energy transfer?

A

Because convection currents cannot be set up

46
Q

What is specific heat capacity?

A

The amount of energy required to raise the temperature of 1kg by 1 degree

47
Q

How does mass affect the specific heat capacity?

A

The greater the mass of an object, the more slowly its temperature increases when it is heated

48
Q

If you had 2kg of copper how much more energy would you need to transfer to raise the temperature compared to 1kg?

A

Twice as much

49
Q

The rate of temperature change in a substance when heated depends on what?

A

Energy transferred to it
Mass
Specific heat capacity

50
Q

How can you reduce the rate of energy transfer out of a home?

(3/6)

A

Fibreglass- reduce energy by conduction
Double glazing- reduce energy transfer by conduction through windows
Drought excluders-reduce energy transfer by convection

51
Q

How can you reduce the rate of energy transfer out of a home?

(2/6)

A

Cavity walls- traps air in small pockets to refuse energy transfer by convection
Aluminium foil behind radiators- reflects infrared radiation back into the room

52
Q

What is a u-value?

A

Tells us how much energy per second passes through a material- the lower the u-value the better

53
Q

The double-glazing for a house costs £3,000 but saves £150 per year in fuel costs. What is its payback time?

A

3000/150= 20 years

54
Q

Ads of solar panels

A

Do not require fuel

They heat water for use in the house

55
Q

Dis ads of solar panels

A

Expensive to buy and install

Water not heated at night

P1 (7 decks)

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