Heat Transfer: Conduction, Convection, and Radiation

Definition and Measurement

• Heat is the transfer of thermal energy from one body or system to another due to a difference in temperature.
• Heat is measured in units of energy, typically in joules (J).

Types of Heat Transfer

• Conduction: transfer of heat through direct contact between particles or molecules.
• Convection: transfer of heat through the movement of fluids.
• Radiation: transfer of heat through electromagnetic waves.

Heat Transfer Mechanisms

• Heat capacity: the amount of heat energy required to change the temperature of a substance by 1°C.
• Specific heat capacity: the heat capacity of a substance per unit mass.
• Latent heat: the heat energy required to change the state of a substance (e.g., melting or boiling).

Laws of Thermodynamics

• Zeroth Law of Thermodynamics: if two systems are in thermal equilibrium with a third system, they are also in thermal equilibrium with each other.
• First Law of Thermodynamics: energy cannot be created or destroyed, only converted from one form to another.
• Second Law of Thermodynamics: the total entropy of a closed system always increases over time.

Heat and Temperature

• Temperature: a measure of the average kinetic energy of particles in a substance.
• Heat and temperature are not the same: heat refers to the transfer of energy, while temperature refers to the measure of that energy.

Applications of Heat

• Heat engines: devices that convert heat energy into mechanical energy.
• Refrigeration: the process of transferring heat from a colder body to a hotter body.
• Thermal insulation: materials used to reduce heat transfer between objects.

Definition and Measurement

• Heat is the transfer of thermal energy between bodies or systems due to a temperature difference, measured in units of energy typically in joules (J).

Types of Heat Transfer

• Conduction occurs through direct particle or molecular contact.
• Convection involves heat transfer through fluid movement.
• Radiation transfers heat through electromagnetic waves.

Heat Transfer Mechanisms

• Heat capacity is the energy required to change a substance's temperature by 1°C.
• Specific heat capacity is the heat capacity per unit mass of a substance.
• Latent heat is the energy required to change a substance's state (e.g., melting or boiling).

Laws of Thermodynamics

• The Zeroth Law of Thermodynamics states that if two systems are in thermal equilibrium with a third system, they are also in thermal equilibrium with each other.
• The First Law of Thermodynamics states that energy cannot be created or destroyed, only converted from one form to another.
• The Second Law of Thermodynamics states that the total entropy of a closed system always increases over time.

Heat and Temperature

• Temperature measures the average kinetic energy of particles in a substance.
• Heat and temperature are distinct concepts: heat refers to energy transfer, while temperature measures that energy.

Applications of Heat

• Heat engines convert heat energy into mechanical energy.
• Refrigeration involves transferring heat from a colder body to a hotter body.
• Thermal insulation materials reduce heat transfer between objects.