Energy Transfers by Heating

Question 1

What is thermal conductivity?

Answer 1

How quickly energy is transmitted through a material by thermal conduction

Question 2

When thermal conductivity is high, what is there more of?

Answer 2

Heat loss

Question 3

What are 2 factors that affect the rate of heat loss from a building?

Answer 3

1. Thickness of walls
2. Thermal conductivity of its walls and roof

Question 4

What is a thermal insulator?

Answer 4

A material with low thermal conductivity.

Question 5

What 3 factors does energy transfer per second (through a material) depend on?

Answer 5

1. The material’s thermal conductivity
2. The temperature difference between the two sides of the material
3. The thickness of the material

Question 6

What is specific heat capacity?

Answer 6

The amount of energy needed to raise the temperature of 1kg of a substance by 1°C

Question 7

What 3 factors does temperature change depend on when a substance is heated or cooled?

Answer 7

1. The substance’s mass
2. The type of material
3. The type of energy transferred to it

Question 8

What type of radiation do all objects emit and absorb?

Answer 8

Infrared

Question 9

When there is more infrared radiation being emitted by an object, what is happening?

Answer 9

Temperature is increasing

Question 10

What is a black body?

Answer 10

A theoretical object that absorbs 100% of the radiation that falls on it.
A perfect black body would:
1. Not reflect or transmit any radiation
2. Be a perfect emitter of radiation

Question 11

What is equal to radiation emitted (for an object at a constant temperature)?

Answer 11

Radiation absorbed

Question 12

How do greenhouse gases heat up the Earth?

Answer 12

They absorb infrared emitted by the Earth’s surface, trap it in our atmosphere and then re-emit it back to Earth.

Question 13

What are the greenhouse gases?

Answer 13

Methane, carbon dioxide, water vapour