Heat Transfer: Conduction and Convection

Definition of Heat

• Heat is a form of energy that is transferred from one body to another due to a difference in temperature.
• It is a form of kinetic energy associated with the motion of particles in a substance.

Types of Heat Transfer

• Conduction: heat transfer through direct contact between particles or molecules.
  • Occurs in solids, where particles vibrate and collide, transferring energy.
• Convection: heat transfer through the movement of fluids.
  • Occurs in liquids and gases, where heated fluid expands and rises, carrying energy away from the source.
• Radiation: heat transfer through electromagnetic waves.
  • Occurs through electromagnetic radiation, such as light and radio waves.

Heat Transfer Mechanisms

• Thermal Conductivity: the ability of a material to conduct heat.
• Specific Heat Capacity: the amount of energy required to change the temperature of a substance by 1°C.
• Latent Heat: the energy required to change the state of a substance (e.g., melting or boiling).

Heat Units and Measurement

• Joule (J): the SI unit of energy and heat.
• Calorie (cal): a unit of heat energy, defined as the energy required to raise the temperature of 1 gram of water by 1°C.
• Thermometer: a device used to measure temperature.

Applications of Heat

• Heating and Cooling Systems: used in buildings, vehicles, and electronic devices.
• Thermal Energy Generation: used in power plants to generate electricity.
• Cooking and Food Preparation: used in various cooking methods, such as grilling, baking, and boiling.

Definition of Heat

• Heat is a form of energy that is transferred from one body to another due to a difference in temperature.
• It is a form of kinetic energy associated with the motion of particles in a substance.

Types of Heat Transfer

• Conduction: direct contact between particles or molecules transfers heat energy, occurring in solids where particles vibrate and collide.
• Convection: heat transfer occurs through the movement of fluids, where heated fluid expands and rises, carrying energy away from the source, occurring in liquids and gases.
• Radiation: heat transfer occurs through electromagnetic waves, such as light and radio waves.

Heat Transfer Mechanisms

• Thermal Conductivity: measures a material's ability to conduct heat.
• Specific Heat Capacity: the amount of energy required to change the temperature of a substance by 1°C.
• Latent Heat: energy required to change the state of a substance (e.g., melting or boiling).

Heat Units and Measurement

• Joule (J): the SI unit of energy and heat.
• Calorie (cal): a unit of heat energy, defined as the energy required to raise the temperature of 1 gram of water by 1°C.
• Thermometer: a device used to measure temperature.

Applications of Heat

• Heating and Cooling Systems: used in buildings, vehicles, and electronic devices to control temperature.
• Thermal Energy Generation: used in power plants to generate electricity through heat energy conversion.
• Cooking and Food Preparation: heat energy is used in various cooking methods, such as grilling, baking, and boiling.

Heat Transfer

Radiation

• Electromagnetic waves (e.g. light, radio waves) transfer heat through radiation
• No medium required for heat transfer (e.g. air, water)
• All objects emit and absorb radiation, dependent on their temperature
• Examples: sun's heat, heat lamps, thermal imaging

Convection

• Fluid movement (e.g. air, water) transfers heat through convection
• Heated fluid expands, rises, and creates circulation of heat
• Examples: radiator heating, ocean currents, atmospheric circulation

Conduction

• Direct contact between particles or molecules transfers heat through conduction
• Heat energy is transferred between objects in direct contact
• Examples: holding a hot cup, metal spoon in hot soup, CPU heat sink

Temperature

• Average kinetic energy of particles in a substance measures temperature
• Measured in °C, °F, or K
• Scales:
  • Celsius: 0°C (water freezing point), 100°C (water boiling point)
  • Fahrenheit: 32°F (water freezing point), 212°F (water boiling point)
  • Kelvin: 0K (absolute zero), 273K (water freezing point), 373K (water boiling point)
• Temperature affects heat transfer rate, with higher temperatures increasing heat transfer