Heat Transfer Concepts

Heat Transfer

• Heat is energy transferred between objects due to a temperature difference.
• A thermometer measures temperature.
• Temperature is the degree of hotness or coldness of an object.
• Hot objects have fast-moving particles, cold objects have slow-moving particles.
• Heat transfer occurs in three ways: conduction, convection, and radiation.

Conduction

• Conduction is the primary mode of heat transfer in solids.
• Heat transfer occurs by direct contact between objects.
• Example: holding the handle of a hot pan, ironing clothes, heating coals on an electric stove.

Convection

• Convection is heat transfer by the movement of particles of a fluid (liquid or gas).
• The fluids move due to temperature differences, with warmer fluids rising and cooler fluids sinking.
• Example: boiling water, land and sea breezes, using a hair dryer.

Radiation

• Radiation is heat transfer by electromagnetic waves.
• Heat can transfer with or without a material or medium.
• Example: warming hands near a fire, using a microwave to heat food, sunbathing causing sunburn.