- cooking appliances, such as electric kettles, ovens, rice cookers
Ø heating elements are found at the bottom
Ø convection currents would be formed
Ø hot air would rise and heat the food further from the heating elements, food at the bottom would be directly heated by the element
Ø food gets heated up quickly

2.

- air conditioners
Ø installed near the top of the ceiling to facilitate convection currents
Ø rotary fan inside an air conditioner releases cool air into the room
Ø warm air rises to be cooled , denser cool air sinks
Ø cool air then cools us
Ø air is also circulated


3. - refrigerator
Ø freezers are constructed at the top
Ø allows cold air to sink and hot air to rise
Ø helps to cool down the contents inside
- household water systems
Ø water is heated up in the boiler

4.

- hot water system

Ø water is heated up in the boiler
Ø hot water expands and becomes less dense, hence it rises to the upper part of the storage tank ( in red)
Ø cold water from the cistern/cold water supply as well as the cooler water in the storage tank will fall into the boiler
Ø hot water will come out from the hot tap
Ø the overflow/ expansion pipe is attached to the storage tank in case the hot water expands too much and overflows

5. air and sea breezes

~ day
Ø land heats up faster than the sea
Ø hot air (red arrow)above land rises, cold air (blue arrow)above sea sinks
Ø sea breeze

~ night
Ø sea is warmer than land
Ø hot air (red arrow) above sea rises, cold air (blue arrow)above the land sinks
Ø land breeze



7. - hot air balloons
Ø they are able to rise,
Ø the air inside the balloon is heated up
Ø the hot air expands and is less dense than the surrounding air outside
Ø hot air rises, also causing the balloon to rise



applications of radiation :

1.

- greenhouse
Ø greenhouses are used in cold climates to help plants grow better by trapping heat
Ø in the day, infrared radiation from the sun passes through the glass roof of the greenhouse
Ø warms up the plants
Ø the contents starts to get warm and emit infrared radiation
Ø the radiation emitted cannot pass through the glass roof
Ø it gets trapped and builds up over time, causing the temperature in the greenhouse to increase

2. - kettles, teapots
Ø brightly polished, light coloured, smooth surface to reduce heat emission through radiation
Ø can keep liquids hot for a longer time

3. - cooling fins
Ø at the back of the refrigerator, in a car radiator, on a motor bike engine
Ø painted black to radiate heat quickly to the surroundings

5.

- solar panels
Ø dark surfaces to absorb heat

how solar panels work

~heat from the sun warms the water in the pipes

~ water is pumped to the hot water tank

~ heat is also transfered from water in the pipe to water in the tank

~ cooler water is circulated backto the solar panel

· the sheet of glass traps heat
· insulation reduces heat loss to the surroundings

6. - shiny blankets(that marathon runners use)

7. - firefighting suits

8. - houses
Ø in hot countries, people paint their houses white to reduce heat absorption from the sun.

9.

- vacuum flask

Ø designed to keep liquids hot by minimising heat loss through conduction, convection, radiation and evaporation
Ø stopper : made of plastic which is a poor conductor of heat
Ø trapped air (above the liquid) : reduces conduction since air is an insulator of heat
Ø vacuum (between the double glass walls): conduction and convection through the sides are prevented
Ø silvered glass walls: reduces heat loss through radiation, walls reflect radiant heat back into the liquid