Showing posts with label Applications. Show all posts
Showing posts with label Applications. Show all posts
Saturday, July 4, 2009
Thursday, July 2, 2009
Example of Everyday applications with Radiation
1. A fire-fighting suit needs bright and shiny outer layer so that it is slow to absorb heat energy from the fire.
2. During the day, infared radiation from the sun passes through the glass roof of the greenhouse. This warms up the soil and plants in the greenhouse. As the contents in the greenhouse get warm, they start to emit infared radiation. The infared radiation emitted by the contents in the greenhouse is slightly different compared to the infared radiation emitted by the Sun and is unable to pass through the glass roof. Therefore. the infared radiation emitted by the contents in the greenhouse gets trapped. The amount of infared radiation in the greenhouse gets built up over time, thus, causes the temperature in the greenhouse to rise.
2. During the day, infared radiation from the sun passes through the glass roof of the greenhouse. This warms up the soil and plants in the greenhouse. As the contents in the greenhouse get warm, they start to emit infared radiation. The infared radiation emitted by the contents in the greenhouse is slightly different compared to the infared radiation emitted by the Sun and is unable to pass through the glass roof. Therefore. the infared radiation emitted by the contents in the greenhouse gets trapped. The amount of infared radiation in the greenhouse gets built up over time, thus, causes the temperature in the greenhouse to rise.
Example of Everyday applications with Convection
1. Car engines: Cooled by convection currents in the water pipes. Water is a very good substance to carry the unwanted heat away from the engine to the radiator.
2. The sun can cause very large convection currents of air. This flow of air is wind. In daytime, the land has a higher temperature than the sea. The warm air rises over the land and the coolair falls over the sea. So we feel a breeze from the sea.
3. Rising air over the land are convection currents and are used by glider pilots to keep their gliders in the sky.
4. Air conditioners are installed near the ceiling of the room, to allow the setting up of convection currents. The air-conditioner releases cool dry air into the room. As cool air is denser, it sinks. The warm air, being less dense, will rise. The air circulated and the temperature of the air will eventually fall to the desired value.
5.
Inversion layer. Air near ground is more dense than air higher up; no convection currents to lift pollutants.http://www.blogger.com/post-edit.g?blogID=8541793538969815640&postID=8144138354297716640
6.
Hot room air is forced outside, while cooler air replaces it.
2. The sun can cause very large convection currents of air. This flow of air is wind. In daytime, the land has a higher temperature than the sea. The warm air rises over the land and the coolair falls over the sea. So we feel a breeze from the sea.
3. Rising air over the land are convection currents and are used by glider pilots to keep their gliders in the sky.
4. Air conditioners are installed near the ceiling of the room, to allow the setting up of convection currents. The air-conditioner releases cool dry air into the room. As cool air is denser, it sinks. The warm air, being less dense, will rise. The air circulated and the temperature of the air will eventually fall to the desired value.
5.
Inversion layer. Air near ground is more dense than air higher up; no convection currents to lift pollutants.http://www.blogger.com/post-edit.g?blogID=8541793538969815640&postID=8144138354297716640
6.
Hot room air is forced outside, while cooler air replaces it.
Monday, June 15, 2009
Example of Everyday applications with Conduction
Good conductor of heat:
Cooking pans, kettles, heat exchangers
Good insulator of heat:
Handles of appliances and utensils. table mats, woollen clothes, fibre glass
Fibreglass, felt and expandedpolystyrene foam are used for home insulation.It traps large amounts of air.This prevents heat from passing through the ceiling easily.
Why air?Reason: air is a poor conductor of heat.
Cooking pans, kettles, heat exchangers
Good insulator of heat:
Handles of appliances and utensils. table mats, woollen clothes, fibre glass
Fibreglass, felt and expandedpolystyrene foam are used for home insulation.It traps large amounts of air.This prevents heat from passing through the ceiling easily.
Why air?Reason: air is a poor conductor of heat.
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