Physics P1 (Heating and cooling)

Energy transfer by heating

Heat can be transfered by:

• Convection
• Radiation
• Conduction

All objects emit and absorb thermal/infared radiation. The hotter an object is, the more infrared radiation it emits.Infrared radiation is a type of electromagnetic radiation, which involves waves. This means that radiation can even pass through the vacuum of space.

Type of surfaceAbility to emit infrared radiationAbility to absorb infrared radiation dark, matt (dull) good good light, shiny poor poor

Light, shiny surfaces are also good reflectors of infrared radiation.

Conduction

Heat energy can move through a substance by conduction. Metals are good conductors of heat but non-metals and gases are usually poor conductors of heat. Poor conductors of heat are called insulators.

Convection

Convection occurs when particles with a lot of heat energy in a liquid or gas move and take the place of particles with less heat energy. Heat energy is transferred from hot places to cooler places by convection. Particles which are hot have a low density and particles which are cold have a high density.

Factors effecting the rate of evaporation and condensation

The rate of condensation increases if the temperature of the gas is decreased. On the other hand, the rate of evaporation increases if the temperature of the liquid is…