Convection

• Convection is the transfer of heat by the circulation of currents from a hotter to cooler region.

• Convection currents only occur in liquids and gases because it involves movement of fluid particles.

• Convection is used in our daily lives as well as for natural things.

Convection

• Convection involves two processes: Diffusion and Advection• Diffusion is the random motion of the

individual particles in the fluid.• Advection is the transportation of heat by

the large-scale motion of currents in the fluid.

Convection

AdvectionDiffusion

Convection in liquid

Convection in gas• The smoke particles diffusing.

A B

A Smoke box

Sea Breeze in the day• Sea breeze is a wind from the sea caused by the movement of air particles.

The movement is caused by temperature differences between land and water.

Land breeze in the night

Oven• Forced convection is used in convection ovens

where fans circulate the hot air around the food

Rising of a hot-air balloon

Rising of gliders

Cooling of a room by an air conditioner

Refrigerator

Ventilation of room

Boiling of water

Heating of water in a household water system

Home water heater system

Q1. Why does the foil spiral spin when the

flame is placed below it?

•When the cool air is warmed up by the flame, it rises, thus, the cool air rushes in underneath to fill the space and air currents are created. The currents make the convection curler turn.

Q2. Can convection take place in a solid?

•No, convection occurs in a environment such as air or liquid. Solids can only conduct heat.

Q3. Why are air conditioners not installed near the floor

of a room?

•The cold air from the air conditioner sinks, while the warm air, being lighter, rises to replace it. This creates a circulatory movement of air.

Done by:Claudia

Shireen