Heat Transfer through Conduction

Heat Transfer

• Heat travels directly and quickly to cooler objects nearby, including nearby gas or liquid particles (atoms or molecules).
• Heat can be felt through direct contact, such as Carlo feeling the heat on his hands when sitting close to the fire.

Conduction

• Conduction is the process of thermal transfer within an object or between a hot object and a cooler object when they come in direct contact.
• Heat is transferred by increasing the motion of particles in solid objects, happening best in solids, especially metals.
• Although conduction can occur in liquids and gases, it is much slower than in solids.

Convection

• Convection is the process of thermal transfer when the heat from a hot object or heat source is carried by the movement of a heated liquid or gas, such as water or air.
• The heated liquid or gas rises, carrying the heat in its particles.

Radiation

• Radiation is the process of thermal transfer through infrared electromagnetic waves.
• This transfer of heat does not require a substance, or medium, to carry the heat energy.
• Heat always flows from a higher-temperature object to a lower-temperature object.

Heat and Temperature

• Heat is an energy, measured in units of energy—joules (J) or calories (cal).
• Temperature is a measure of the average kinetic energy of particles in an object or system, indicating how hot or cold an object or system is.
• Temperature represents the intensity of thermal energy present in a substance, measured in units that show intensity—degrees Celsius (°C), degrees Fahrenheit (°F), or Kelvins (K).

Key Concepts

• The three ways that heat can be transferred from one place to another are conduction, convection, and radiation.
• Heat is transferred when particles move and collide, producing thermal energy.
• Heat energy is measured in units of energy, while temperature is measured in units that show intensity.