by Bharwad Singh Murthy HardPussy

Created on: February 16, 2009

Aren't you curious about how heat spreads? Did you think about what exactly happened when you touched something hot?

var ve_publisher = "triond"; var ve_site = "scienceray"; var ve_area = "scienceray"; var ve_width = 300; var ve_height = 250; var ve_alternate = "http://www.scienceray.com/videoegg_alt.php?zone_id= 162"; document.write("<\/script>");

Heat transfer

is separated into three sections. Heat can be transferred from a warmer to cooler object by conduction, convection, and radiation. Each of the various types are similar and different in many ways.

To start out, convection is heat transfer through a fluid (liquid and gas). Convection happens when a fluid is heated. The part nearest the heat source expands. The kinetic energy increases as molecules move faster and contract. The heated fluid becomes less dense. Density is the amount of mass in a volume. The fluid is forced to rise because it is less dense than the cooler, more compact fluid. When it reaches the surface, the warmer liquid starts to diffuse and expands to the sides. At the surface, it cools down and the fluid sinks. The heat source then reheats the liquid. The liquid then goes over the same process over and over again. These are called convection currents. Convection currents continue until the heat source has been removed and the molecules are the same temperature. Convection currents are a chain of movement by heat through a liquid when there is a heat source. Unlike radiation, convection can be visible sometimes. Convection, along with radiation and conduction happen near earth's surface. Convection, conduction and radiation all involve a heated object. Convection does not transfer heat through electromagnetic waves. Some examples of convection are in the asthenosphere, troposphere, and even at homes. In the asthenosphere (a layer between 100-200 miles below the earth's crust, right above the mantle) the magma in the asthenosphere which is nearest the mantle rises because it is heated by the mantle. Once it reaches the top, it expands to the sides, the fluid sinks, the fluid gets heated again. Convection causes more warming than radiation and conduction in the troposphere (the lowest layer of atmosphere). The air near the ground gets heated and the molecules have more kinetic energy. They crash into each other and expand farther out. When it moves farther out, it becomes less dense. The cooler more dense air stays at the bottom, while the warmer flows into the troposphere. Some home appliances
that

• 1
• 2
• Next Page >>