Heat Transfer – Conduction, Convection and Radiation

 Heat Transfer – Conduction, Convection and Radiation

Thermal Energy Transfer

- Thermal energy can be transferred in three main ways: conduction, convection, and radiation.

 

Heat Conduction

- Conduction is the movement of heat within a solid object.

- Conduction occurs when objects are touching, such as a kettle on a stove.

- Heat from the flame moves through the metal of the kettle to the water inside.

- Butter melting on a frying pan is another example of heat conduction.

 

Heat Conduction

- Heat conduction occurs through direct contact when heat moves from a warmer object to a cooler object.

- When you lick an ice cream, it feels cold because heat conducts from your tongue to the ice cream.

- Heat conduction is the movement of heat in liquids and gases.

 

Convection

- Convection is the movement of heat in liquids and gases.

- In a hot air balloon, the air is heated by the burner and rises inside the balloon.

- As the hot air rises, the cooler air falls, creating a current within the balloon.

- The convection current causes thermal energy in the air to spread. Cooling a Room with an Air Conditioner

- On a hot day, an air conditioner can be used to cool down a room

- The cold air that blows out from the air conditioner circulates the room and creates convection currents

Radiation

- Radiation is the process of heat moving from a warmer object to a cooler object without affecting the medium in between.

- Radiation uses electromagnetic waves to emit heat waves that can be reflected, absorbed, or transmitted through a colder object.

- This process doesn't require a medium, unlike conduction and convection.

- For example:- The sun's rays can warm the Earth even after passing through the mesosphere.

Heat Transfer through Conduction and Convection

- Heat moves from the warmer air to the colder air, which makes the air in the room cooler

- For the thermal energy to move by conduction and convection, it must travel through matter

 

Heat Transfer between the Sun and the Earth

- The heat transfer between the sun and the earth occurs through conduction and convection heat        Transfer and the Sun's Warmth

- The sun warms the Earth and other planets through radiation.

- Radiation is the transfer of energy through electromagnetic waves.

 

Radiation vs. Convection

- Radiation is the direct transfer of heat, as seen when a fireplace warms a person.

- Convection is the transfer of heat through the movement of a medium, such as the air being warmed in a room by a fireplace.

- Both radiation and convection play a role in how the sun's heat reaches and warms the Earth.

 

Radiant Heat

- Radiant heat is the warmth felt when placing your hands near an electric heater or other heat source.

- Radiant heat is the direct transfer of thermal energy through electromagnetic waves, without needing a physical medium.

- This is the primary mechanism by which the sun's heat reaches and warms the Earth and other planets in the solar system. Heat Transfer

- Heat can be transferred in three main ways: conduction, convection, and radiation.

- Conduction is the transfer of heat through direct contact between objects or materials, such as heat moving through the metal of a kettle to the water inside.

- Convection is the transfer of heat through the movement of a fluid, such as the circulation of hot water within a kettle.

- Radiation is the transfer of heat through electromagnetic waves, such as the heat from a heater or campfire.

 

Heat Transfer in a Kettle

- When water in a kettle is heated, thermal energy moves through the metal of the kettle by conduction.

- The thermal energy then moves around the water through convection, as the water circulates and mixes.

- Finally, the heat leaves the kettle and is transferred to the surrounding environment through radiation.

 

Conclusion

- Heat can be transferred through various mechanisms, including conduction, convection, and radiation.

- These processes can be observed in everyday examples, such as water heating in a kettle.