Energy Transfer By Heating

Question 1

All objects emit…

Answer 1

Infrared radiation

Question 2

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

Answer 2

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

Question 3

What is infrared radiation?

Answer 3

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

Question 4

What is vacuum?

Answer 4

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

Question 5

Can infrared radiation travel through a vacuum?

Answer 5

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

Question 6

Does the transfer of energy by infrared radiation involve particles?

Answer 6

NO!!

Question 7

Do all objects emit infrared radiation?

Answer 7

Yes

Question 8

What are good absorbers of infrared radiation?

Answer 8

Dark, Matt surfaces

Question 9

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

Answer 9

Yes the black surface will be hitter

Question 10

What are good emitters of infrared radiation?

Answer 10

Dark, Matt surfaces

Question 11

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

Answer 11

Dull black surfaces

Question 12

Which kind of surfaces are good reflectors?

Answer 12

Light, shiny surfaces

Question 13

Why are houses in hit countries often painted white?

Answer 13

Because it is a poor absorber of infrared radiation

Question 14

Why are pipes on a fridge usually painted black?

Answer 14

They are the best emitters

Question 15

How can we make substances change between states?

Answer 15

Heating or cooling

Question 16

In a solid…

Answer 16

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

Question 17

In a liquid…

Answer 17

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

Question 18

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

Answer 18

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

Question 19

In a gas…

Answer 19

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

Question 20

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

Answer 20

Less

Question 21

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

Answer 21

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

Question 22

Where does conduction mainly occur?

Answer 22

Solids

Question 23

Are liquids and gases good or poor conductors?

Answer 23

Poor

Question 24

Explain theprocess of conduction

Answer 24

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

Question 25

Explain conduction in a metal

Answer 25

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

Question 26

What are poor conductors called?

Answer 26

Insulators

Question 27

What materials are good insulators?

Answer 27

Wool and fibreglass because they contain trapped air

Question 28

Why are materials that trap air good insulators?

Answer 28

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

Question 29

What does convection occur in?

Answer 29

Fluids, gases and liquids

Question 30

What is convection?

Answer 30

The circulation of a fluid caused by heating it

Question 31

Explain convection

Answer 31

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

Question 32

Why doesn't convection occur in solids?

Answer 32

Because solids have fixed positions and cannot flow

Question 33

Why does a fluid become less dense when heated?

Answer 33

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

Question 34

Where do convection currents occur on a very large scale?

Answer 34

Onshore and offshore breezes

Question 35

What is evaporation?

Answer 35

When a liquid turns to a gas

Question 36

Why does evaporation occur?

Answer 36

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

Question 37

Why does evaporation cause cooling?

Answer 37

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

Question 38

What increases the rate of evaporation?

Answer 38

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

Question 39

What is condensation?

Answer 39

When a gas turns to a liquid

Question 40

What increases the rate of condensation?

Answer 40

Increasing surface temp | Reducing surface temperature

Question 41

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

Answer 41

The greater the rate at which energy is transferred

Question 42

What other factors affect rate of energy transfer?

Answer 42

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

Question 43

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

Answer 43

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

Question 44

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

Answer 44

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

Question 45

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

Answer 45

Because convection currents cannot be set up

Question 46

What is specific heat capacity?

Answer 46

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

Question 47

How does mass affect the specific heat capacity?

Answer 47

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

Question 48

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

Answer 48

Twice as much

Question 49

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

Answer 49

Energy transferred to it Mass Specific heat capacity

Question 50

How can you reduce the rate of energy transfer out of a home? (3/6)

Answer 50

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

Question 51

How can you reduce the rate of energy transfer out of a home? (2/6)

Answer 51

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

Question 52

What is a u-value?

Answer 52

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

Question 53

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

Answer 53

3000/150= 20 years

Question 54

Ads of solar panels

Answer 54

Do not require fuel | They heat water for use in the house

Question 55

Dis ads of solar panels

Answer 55

Expensive to buy and install | Water not heated at night