Transfer of thermal energy
- Created by: cookieshypiggy
- Created on: 29-04-13 12:56
View mindmap
- Transfer of thermal energy
- Convection
- Occurs mostly in fluids (Liquids and Gases)
- Heat is transferred through the movements of heated particles
- The heated portions of the fluid becomes less dense and rise up, while the colder portions of fluids become denser and sink.
- This creates the convection current
- Applications
- Electric kettle
- Heating coil is placed at the bottom to allow hot water to rise and cold water to sink
- Air conditioners
- They are fixed close to the ceiling as cold air sinks
- Electric kettle
- Conduction
- Occurs mostly in solids
- Heat is transferred through the vibrations of particles or diffusion of free electrons in solids
- A material with a high value of thermal conductivity is a better conductor of heat
- Metals have higher thermal conductivity, hence metals are better conductors compared to non-metals and air
- Applications
- Metals (eg. stainless steel/aluminium)
- Used as cooking utensils and saucepans
- Insulating materials (eg. wood/plastic)
- Used for handles of saucepans and cooking utensils
- Metals (eg. stainless steel/aluminium)
- Radiation
- Heat is transferred by electromagnetic waves or infrared waves
- No medium required for heat transfer
- Factors affecting the rate of radiation
- colour and texture of surface
- Dull and black are better emitters and absorbers of radiation
- Surface temperature
- Higher temperature =higher rate of radiation
- Surface area
- Larger surface area = higher rate of radiation
- colour and texture of surface
- Applications
- Wearing brightly-coloured clothing on a hot day
- Bright surfaces reflect most of the radiant heat
- Greenhouse used i cold countries
- keep heat in, warming the plants
- Wearing brightly-coloured clothing on a hot day
- Convection
Comments
No comments have yet been made