Test - Thermal Conductivity Flashcards
What is thermal conductivity
It is the rate at which heat is transferred by conduction through a cross section area of a material
What is the units for energy
It is joule ( J )
To improve energy efficiency what do you need to do
Reduce waste energy
Energy efficiency percent =
= (useful energy out / total energy in ) x 100 percent
On a tv if the light is 119 J sound is 1J and electricity is 200 J
calculate the efficiency of the television as a percentage and a decimal
0.6 or 60 percent
How can we improve efficiency
By insulation or lubrication
How do you work out this equation
A blender is 70 percent efficient . It has a total input power of 600W. Caculate the useful output power
1) change the efficiency from a percentage to a decimal
2) rearrange the equation for useful power output
3) stick in the numbers you are given
What effects the cooling of a building
The thickness and the thermal conductivity of its walls
How is the rate of a cooling building affected by the thickness and the thermal conductivity of its walls
The thicker the wall the thicker barrier to the heat leaving the building. The high the conductivity the quicker the heat is conducted out of the building
