P2 Flashcards
What are the best conductors of thermal energy
Metals
Why are wool and fibreglass good insulators
They trap air
What does the rate of thermal energy transferred through a material depend on
-Temp difference across material
-thickness of material
What must a material have to reduce the rate of thermal energy transferred
-have a low thermal conductivity
-be as thick as possible
What does an object at a constant temperature do
Emits infrared radiation at the same rate it absorbs it
What is a perfect black body
An object that absorbs all the radiation it hits
What is black body radiation
The radiation emitted by a black body
How does an object increase in temperature
Absorbs radiation at a greater rate than it emits it
What will an surface with a light shiny surface do
Emits radiation at a lesser rate than an object with a dark surface
What does the temperature of the earth depend on
The rate at which radiation from the sun is reflected or absorbed by the earths atmosphere
What is specific heat capacity
The amount of thermal energy needed to heat a 1kg object by 1 degree
what does fibre glass loft insulation do
reduces the rate of energy transfer through the roof
what does cavity wall insulation do
reduces rate of energy transfer through the outer walls
what does aluminium foil do
placed behind radiators to reflect infrared radiation back into the room
how does the temperature of an object affect the rate at which it emits infrared radiation
the higher the objects temperature the greater rate of emission of infrared radiation
