P2 - Energh Transfers by Heating Flashcards
Which materials have low thermal conductivity
thermal insulators
three factors that determine the rate of thermal energy transfer through a material
thermal conductivity of material, temperature difference, 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, the temperature difference between the two sides of the wall/roof
define specific heat capacity
amount of energy needed to raise the temperature of 1kg of a material by 1°C
what is infrared radiation
type of electromagnetic radiation
what is the relationship between the temperature of an object and it’s 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 absorbed than emitted
what is a black body
theoretical object that absorbs 100% of the radiation that falls on it, and does not reflect or transmit any radiation
three greenhouse gases
water vapour, carbon dioxide and methane
human activities that increase the amount of greenhouse gases released
deforestation, burning fossil fuels and livestock farming
why do greenhouse gases increase the earths temperature
the earths surface absorbs and re-emits radiation from the sun, which greenhouse gases then absorb - they re-emit this radiation back towards earths surface
thermal conductivity of a material
how quickly energy is transmitted through it by thermal conduction
change in thermal energy (j) equation
mass x specific heat capacity (J/kg°c) x temperature change
power equation
potential difference x current
