Heat+Transfer

How is Heat Transferred? The three ways heat can be transferred from one object to another:
 * ** Conduction **
 * ** Convection **
 * ** Radiation **

**CONDUCTION**: media type="youtube" key="77R4arwD8G8" height="345" width="420" align="center"

Conduction takes place when one part of a solid material is heated. The particles in this part vibrate (shake) faster and hit their neighbors. When collisions take place, the energy is transferred to the neighboring particles causing the energy to travel through the solid. This is similar to the way energy passes along a set of tumbling dominoes.

Heat is transferred from the warmer object to the cooler one until they are both at the same temperature.

Some substances conduct heat more easily than others. Metals are very good conductors of heat, while Styrofoam is a poor conductor of heat. (A poor conductor is a good insulator). You experience heat transfer by conduction when you touch something that is hotter or colder than your body. media type="custom" key="10324430"

media type="youtube" key="5pG-tkbQgMo" height="345" width="420" align="center"
 * CONVECTION: **

Convection currents are produced when liquids and gases are heated. If you carefully watch water being heated in a pot on a stove, you will see dust particles and bubbles moving in the water. The convection currents in the water carry the bubbles and dust.

Convection currents are caused by the expansion of water due to its rise in temperature. The hotter water becomes less dense and rises, while the colder water is denser and sinks. This starts the cycle of convection current. media type="custom" key="10297195" **RADIATION:** media type="youtube" key="2JZciWtK6vc" height="345" width="420" align="center"

Both conduction and convection require matter to be in physical contact (touch each other) to transfer heat. Radiation is a method of heat transfer that does not need any contact between the heat source and the heated object. For example, we feel heat from the sun even though there are 93 million miles of empty space between the sun and Earth.

Heat from the sun is transferred to Earth in the form of light. Light is a form of thermal radiation. Heat can only be transmitted though empty space by thermal radiation. Thermal radiation consists of waves that travel at the speed of light.

You feel radiation from a bonfire across a distance of several meters. The heat is being transferred to you by radiation. media type="custom" key="10297423" align="center"