P1-Chapter 1 Energy Transfer By Heating

Question 1

Infrared Radiation

Answer 1

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

Question 2

Emit

Answer 2

Give out radiation

Question 3

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

Answer 3

The higher the temperature of an object the greater the rate at which it emits infrared radiation

Question 4

What is a vacuum?

Answer 4

A vacuum is a region that does not contain anything at all, not even gas particles

Question 5

Why are house in hot countries often painted white?

Answer 5

Houses in hot countries are painted white because white is the worst absorber of infrared radiation

Question 6

Why are the pipes on the back of the fridge usually painted black?

Answer 6

Because black surfaces are the best emitters of infrared radiation

Question 7

Absorber

Answer 7

A substance that takes in radiation

Question 8

Reflector

Answer 8

A substance that reflects radiation

Question 9

Emitter

Answer 9

A substance that gives out radiation

Question 10

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

Answer 10

The particles in a liquid are in contact with each other but are not held in fixed position like those in a solid

Question 11

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

Answer 11

The particles in a gas are much farther apart and move around much faster than those in a liquid

Question 12

Why are saucepans often made of metal with wooden handles?

Answer 12

The metal base of the saucepan is a good conductor so heat is conducted quickly to the food in the pan. The wooden handle is a poor conductor so it prevents someone picking up the saucepan getting burnt

Question 13

Why are materials that trap air good insulators?

Answer 13

Air is a poor conductor so materials that trap air are good insulators

Question 14

Conduction

Answer 14

Transfer of energy from particle to particle in matter

Question 15

Conductor

Answer 15

Material/object that conducts

Question 16

Free electron

Answer 16

Electron that moves about freely inside a metal and is not held inside an atom

Question 17

Insulator

Answer 17

Material/object that is a poor conductor

Question 18

Why doesn’t convection occur in solids?

Answer 18

Convection does not occur in solids because the particles are held in fixed positions and not able to flow

Question 19

Why does a fluid become less dense when it is heated?

Answer 19

A fluid becomes less dense when heated because it expands, so there is the same mass of material in a larger volume

Question 20

Convection

Answer 20

Transfer of energy by the bulk movement of a heated fluid

Question 21

Convection current

Answer 21

The circular motion of matter caused by heating in fluids

Question 22

What effect would decreasing the surface area of a liquid have on its rate of evaporation?

Answer 22

Decreasing the surface area of a liquid would decrease the rate of evaporation

Question 23

What effect would decreasing the surface area of a liquid have on its rate of condensation?

Answer 23

Decreasing the surface area would decrease the rate of condensation

Question 24

Why does painting an object dull black maximise the rate of energy transfer?

Answer 24

Painting an object dull black maximises the rate of energy transfer, because dull black surfaces are the best emitters of radiation

Question 25

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

Answer 25

Trapping air in small pockets minimises the rate of energy transfer because convection currents cannot be set up

Question 26

The specific heat capacity of oil is 2100J/Kc how much energy is needed to raise the temperature of 1kg of oil by 1.c ?

Answer 26

2100x1x1=2100 J

Question 27

The specific heat capacity of water is 4200J/Kc how much energy is needed to raise the temperature of 2kg of water by 1c ?

Answer 27

4200x2x1=8400 J

Question 28

What is the equation for specific heat capacity?

Answer 28

``` E=MxCx0 E- is energy transferred J M- is mass KG C- is the specific heat capacity J/KG c 0- is the temperature change 'C ```

Question 29

Why is fibreglass a good insulator?

Answer 29

Fibreglass is a good insulator because it contains trapped air

Question 30

Why are the pipes that contain be water in a solar heating panel often painted black?

Answer 30

The pipes that contain the water in a solar heating panel are often painted black because black is the best absorber of radiation

Question 31

What is the best colour for a central heating radiator, glossy white or dull black?

Answer 31

Dull black

Question 32

Why does a solid have a fixed volume?

Answer 32

All the particles are held together in fixed positions

Question 33

When a liquid evaporates, why is the average kinetic energy of the remaining molecules reduced?

Answer 33

The most energetic molecules leave the liquid, so the average kinetic energy of the remaining molecules is reduced

Question 34

Which types of energy transfer involve particles?

Answer 34

Conduction, convection and evaporation involve particles

Question 35

What happens to the rate of energy transfer between an object and its surroundings if the temperature difference between them is reduced?

Answer 35

If the temperature difference is reduced, the rate of energy transfer decreases

Question 36

How does energy from the sun reach the earth?

Answer 36

Energy from the sun reaches the earth as radiation that travels through space

Question 37

How does the colour of a surface affect the rate of conduction?

Answer 37

The colour of a surface has no effect on the rate of conduction

Question 38

Why are gases poor conductors?

Answer 38

Gases are poor conductors because the particles are far apart

Question 39

Why are metals the best conductors?

Answer 39

Metals are the best conductors because they contain free electrons

Question 40

What is convection?

Answer 40

Convection is the movement of energy through a fluid by movement of the fluid itself

Question 41

How does cavity wall insulation reduce energy transfer from a house?

Answer 41

Cavity wall insulation traps the air in the cavity pockets, so preventing convection currents from being set up

Question 42

The specific heat capacity of water is 4200J/kg 'c how much energy is needed to raise the temperature of 3kg of water by 4'c

Answer 42

The energy needed is 50,400 J