Transfer of Thermal Energy Flashcards
Why do Objects Feel Hot or Cold?
Thermal Energy flows from a region of higher temperature to a region of lower temperature. Your hand in a warm bucket will have heat enter your hands, the inverse is true.
What is conduction?
It is the transfer of thermal energy through solids.
What is thermal conductivity?
It is dependent on how quickly thermal energy is transferred. Metals are good thermal conductors due to the free electron diffusion. Polystyrene and Fiberglass are the opposite, as they contain gas.
Why are liquids and gases bad conductors?
The particles in them are farther apart, making heat different to transfer.
What is Convection?
Convection is the transfer of thermal energy in fluids (gas and liquids).
Bottom is heated → fluid becomes less dense → rises to the top → makes denser liquids fall to the bottom → cycle.
What is thermal radiation?
Thermal Radiation (Infrared Radiation) is the transfer of thermal energy in the form of electromagnetic waves which can travel through vacuums.
How are emission and absorption investigated through different surfaces?
How do different surfaces emit thermal radiation?
Black, Matte Surfaces emit thermal radiation at faster rates.
Silver, Shiny surfaces emit them slower.
How do different surfaces absorb infrared radiation?
Black, matte surfaces absorb radiaton faster, the inverse is true for silver, shiny surfaces
Applications of The Thermal Radiations Surfaces:
Shiny, Silver: Prevent Marathon Runners from having Hypothermia. Outer layer reduces thermal radiation absored and the inner layer keeps thermal radiation.
What factors affect the emission and absorption of thermal radiation?
- Surface and Texture
- Surface Area
- Surface Temperature
Application of Thermal Conductors:
Good Thermal Conductors
- Cooking Pans
- Soldering Irons
Bad Thermal Conductors
- Pan Handles
- Double Glazed windows
Consequence of Conduction, things can also cool extremely quickly
