P1.1 Heating and Energy Transfer

Question 1

What happens when a metal conducts heat? (3)

Answer 1

D electrons gain Ek.
MOVE through the metal.
TRANSFER energy by colliding with other ions

Question 2

Describe the process of convection (5)

Answer 2

A fluid is HEATED, EXPANDS, gets LESS DENSE, RISES. Warm fluid is replaced by cooler denser fluid.

Question 3

What does the rate at which an object transfers energy by heating depend on? (3)

Answer 3

SA:V ratio
MATERIAL from which the object is made
The NATURE of the SURFACE with which the object is in contact

Question 4

How can you reduce heat loss from a building? (4)

Answer 4

Aluminium foil behind radiators
Cavity wall insulation
Double glazing
Loft insulation

Question 5

What is the purpose of putting aluminium foil behind a radiator?

Answer 5

Reflects heat radiation away from the wall

Question 6

What does loft insulation do?

Answer 6

Air between fibres (in fibreglass) reduce heat loss by CONDUCTION

Question 7

How does cavity wall insulation reduce heat loss?

Answer 7

It traps air in small pockets, reducing heat loss by CONVECTION (the current cannot be set up)

Question 8

How do double-glazed windows containing a vacuum reduce heat loss?

Answer 8

Reduces heat transfer by CONVECTION because the air cannot move

Question 9

How do double-glazed windows containing dry air reduce heat loss?

Answer 9

Dry air is a good insulator so reduces heat loss through CONDUCTION

Question 10

Light, shiny surfaces are poor emitters and absorbers of infrared radiation. What do light shiny surfaces do to infrared radiation?

Answer 10

Reflect it

Question 11

How does the difference in temperature between an object and its surroundings affect the rate of heat transfer?

Answer 11

The bigger the temperature difference between an object and its surrounding, the faster the rate of heat transfer

Question 12

The lower the U-Value…

Answer 12

…the more effective the insulator