Energy transfers by heating Flashcards
What does a material’s thermal conductivity tell you?
How well it conducts heat.
Which materials have low thermal conductivity?
Thermal insulators.
Give three factors that determine the rate of thermal energy transfer through a material.
Thermal conductivity of material, temperature difference and thickness of material.
What factors affect the rate of heat loss from a building?
Thickness of walls and roof, thermal conductivity of walls and roof and the temperature difference between the two sides of the wall/roof.
Define specific heat capacity.
The total amount of energy needed to raise the temperature of 1kg of a material by 1*C.
What is infrared radiation?
A type of electromagnetic radiation.
What is the relationship between the temperature of an object and its emission of infrared radiation?
The higher the temperature of an object, the more infrared radiation emitted in a given time.
What can you tell about an object that absorbs and emits infrared radiation at the same rate?
It is at a constant temperature.
Compare the amount of infrared radiation emitted and absorbed by an object that is increasing in temperature.
More infrared radiation is absorbed that emitted.
What is a black body?
A theoretical object that absorbs 100% of the radiation that falls on it, and does not reflect or transmit any radiation.
Name the three greenhouse gases.
Water vapour, carbon dioxide and methane.
What are some human activities that increase the levels of greenhouse gases released?
Deforestation, burning fossil fuels and livestock farming.
Why do greenhouse gases increase the Earth’s temperature?
The Earth’s surface absorbs and re-emits radiation from the Sun, which greenhouse gases then absorb- they re-emit this radiation back towards the Earth’s surface.
