P2 Conduction, Radiation and SHC Flashcards
What does thermal conductivity mean?
The rate at which an object transfers heat energy.
How to calculate change in thermal energy?
Change in thermal energy = mass x specific heat capacity x temperature change
What is specfic heat capacity measured in?
J/Kg°C
What is specific heat capacity?
The amount of energy required to raise the temperature of 1Kg of a substance by 1°C.
Metals are the best …… of energy?
Conductors
The thicker the layer of insulating material …….
The lower the rate of energy transfered.
All objects emitt and absorb…..
Infrared radiation
What is blackbody radiation?
Radiation emitted by a body that absorbs all the radiation incident on it.
Explain how carbon dioxide leads to global warming.
Carbon dioxide absorbs longer wavelength infrared radiation from the earth and prevent it escaping into space. It absorbs the heat energy and emitts it back to the surface of the earth.
How do calculate specifc heat capacity?
Specific heat capacity = energy transferred / (mass x temprature change)
How do you carry out the Specific Heat Capacity practical?
1) Wrap the block of metal with an insulator and place it on top of an insulating mat
2) Place the thermometer in the metal and record the inital temperature
3) Record the current and volatge you are using as well
4) After one minute record the temperature and temperature change
5) Repeat for every minute until 15-20 mins has gone by
What is efficiency?
Efficiency tells us how much energy is transferred to useful energy and how much energy is wasted.
Suggest why the actual energy transferred is more than the value calculated?
Energy will be transferred by heating to the suroundings.
What is temperature?
The average amount of kinetic energy existing in an object.
What is a perfect black body?
An object that absorbs all of the radiation that hits it.
they don’t reflect or transmit any radiation
