The Transfer of Heat

Energy

What is ENERGY?

• Energy is the ability to make things move or change.

• Matter is made up of particles that are always moving.

• Thermal Energy is the energy of these moving particles.

• We feel Thermal Energy through heat.

Heat Transfer

• Movement of heat from a warmer object to a cooler object is called Heat Transfer.

• An object becomes cooler as heat leaves it.

• However, an object becomes warmer as heat moves into it.

Thermal Energy

• 3 types• Conduction• Convection• Radiation

Conduction

• Conduction is the transfer of thermal heat between things that are touching.

• Example – walking hot sand- your feet are cooler and they become warmer as you walk on the hot sand.

Conduction Examples

• Heating water on an electric stove. The heat moves from the hot surface of the stove to the metal on the pot that is touching the stove.

• Conduction moves thermal energy through a single solid object. The pot gets hot on the bottom, then the middle and finally the top.

• Metals are conductors (Iron, Silver and Copper)• A conductor is a material that heat can move

through easily.

Insulators

• INSULATOR are objects which can not pass electricity or heat through them.

• The insulators can't pass heat due to less or absence of free electrons. for example paper, wood, rubber etc.

Convection

• Convection is the transfer of thermal energy. • If you are heating water on a stove, it is the

constant rising and sinking of warm and cool water because of convection currents.

• Cool water

• Warm water

Convection in the Atmosphere

• Convection currents also move that through the atmosphere because warm air is lighter so it rises and spreads and cold air is heavier and sinks. This is responsible for the uneven heating of air in the atmosphere.

• Cold Air Warm Air

Convection example

• Example:• Bobby is standing in a swimming pool and

notices that the water around his feet is cooler than the water at the surface. Convection is the process that causes the difference in temperature.

Radiation

• The transfer of energy by electromagnetic waves is called Radiation.

• Energy is transferred through waves of energy.• The sun is the main source of electromagnetic

waves.

Radiation Examples

• Example:• If people are sitting around a campfire and are

able to feel the heat without touching the fire, this is radiation because the fire is radiated through the air molecules to the people.

Radiation Energy

• It travels through empty space and warms the Earth’s surface.

• Plants use this energy to make food.