Energy Transfers Flashcards
What happens when energy is transferred between different stores?
When energy is transferred between different stores not all of it is transferred into a useful form of energy.
What happens when you use a kettle to boil water?
For example when I use a kettle to boil water electrical energy is transferred into thermal energy to heat the water.
What causes energy to be wasted in this example?
However some energy is also wasted by heating the surrounding air. This energy spreads out to the surroundings and is lost - we say that the energy is dissipated.
What are the three main ways heat is lost from a house?
Conduction convection and radiation.
How is heat lost by conduction in a house?
Heat transfers through solid materials like walls floors windows and the roof.
How can conduction be reduced in buildings?
By using insulating materials that are poor conductors such as cavity wall insulation.
What is cavity wall insulation and how does it work?
It involves placing insulating material between two walls to reduce heat conduction.
How is heat lost by convection in a house?
Warm air escapes through gaps in windows and doors creating convection currents.
How can convection be reduced in buildings?
By sealing gaps with draught excluders and using double glazed windows.
How do double glazed windows reduce heat loss by convection?
They trap air or vacuum between two panes stopping convection as it needs particles.
How is heat lost by radiation in a house?
Infrared radiation is emitted from warm surfaces like walls roofs and windows.
How can heat loss by radiation be reduced?
By using light-coloured or shiny surfaces that are poor emitters of infrared radiation.
