Keeping Houses Warm

Question 0

Insulators are…

Answer 0

Materials that allow heat energy to spread through slowly

Question 1

What is a conductor

Answer 1

A material that allows heat to spread through quickly eg metals

Question 2

What are convection currents

Answer 2

Movement of hot air rising and cooler air taking its place.
Warm air becomes less dense and rises,the particles move quickly away from each other and expand, being replaced by denser air.

Question 3

How do walls lose energy in the home

Answer 3

They absorb heat radiation

Question 4

Energy is lost from SOURCE to…

Answer 4

SINK

Question 5

Energy efficiency measures what

Answer 5

How good an appliance is at converting input energy into useful output energy

Question 6

What does the amount of infrared given out/taken in depend on

Answer 6

How much infrared given out/taken in depends on ITS SURFACE

Transfer of heat energy by electromagnetic waves

Question 7

How does conduction work

Answer 7

It is the transfer of heat energy through a substance from hotter to cooler without substance moving itself. Kinetic energy increases so particles vibrate. Energy transfers and passes along

Question 8

What is radiation (on hot objects)

Answer 8

Transfer of heat energy by electromagnetic waves

Hot objects emit mainly infrared radiation which can pass through a vacuum so no material is needed for the transfer

Question 10

What surface emits more radiation at room temperature

Answer 10

Dark matt

Question 11

Heat can also move as infrared radiation (electromagnetic wave)

What surface reflects infrared

Answer 11

Shiny surfaces

Wont get as hot

Question 11

Which surface is a better absorber of radiation

Answer 11

Dark matte

Question 12

How does fibreglass loft insulation reduce heat loss in the home

Answer 12

Reduces convection and conduction by trapping layers of air between fibres

Question 13

How do reflective foil on walls behind radiators reduce heat loss in the home

Answer 13

Reduces radiation by reflecting infrared heat energy into the room

Question 14

For a television what is the input energy, useful energy and wasted energy

Answer 14

Electrical energy is input
Sound and light energy is output
Heat energy is wasted

Question 15

How does cavity wall insulation reduce heat loss in the home

Answer 15

Reduces conduction and convection by trapping small pockets of air in the foam

Question 15

How does double glazing reduce heat loss in the home

Answer 15

Reduces conduction and convection by trapping air between panes of glass

Question 15

Amount of radiation given out depends on what (in a material)

Answer 15

How much infrared given out/taken in depends on it’s surface

Question 15

Why are metals good conductors

Answer 15

Heat energy is also transferred by free electrons in a metal

They flow, collide with and transfer energy to other atoms increasing their kinetic energy so temperature rises

Question 16

How do draught excluders reduce heat loss in the home

Answer 16

Reduces convection by keeping as much warm air inside as possible

Question 17

What type of heat loss does insulation only prevent

Answer 17

Heat loss by conduction

Question 18

How does convection cause heat loss

Answer 18

Because liquids and gases can easily flow they can transfer heat energy from hotter to cooler regions by their own movement. Cools overall temperature

Fast particles expand and become less dense so rise up to be replaces with denser liquid or gas

Question 19

When heat is lost from a home what is the source and what is the sink

Answer 19

Home is source

Atmosphere is sink

Question 20

Describe particle movement in a hotter object

Answer 20

Fast moving particles

In a solid they vibrate
In a liquid they flow past each other and move further apart

Question 21

Why are refrigerators insulated

Answer 21

To reduce heat gain by conduction or convection

Question 22

Why are curtains good insulators

Answer 22

Trap air between them and window helping to reduce heat energy loss by conduction