Thermal Energy Flashcards
What are the ways in which thermal energy is transferred
- Conduction
- Convection
- Radiation
How does conduction work
When an area of a substance heats up with the user of thermal energy. The particles in that area gain a lot of kinetic energy. These particles then transfer this kinetic energy to other particles that are closer to them. This then continues throughout the entire material.
Why does conduction happen quicker in metals than in heat insulators
Because metals have free electrons in metallic bonds. Therefore, the electrons can easily transfer the thermal energy to the particles close to them.
How does convection occur
In convection, the air at the bottom of the system will get heated up. This air will then reduce in density, causing the air to rise up. The denser cold air then takes place of the warm air and becomes hot and rises.
Convection only occurs in fluid substances like: liquid or gases.
What is thermal radiation
This is the transfer of thermal energy via IR radiation
What makes a good radiator of heat
Matte Black surfaces.
What makes a poor radiator of heat
Shiny Surfaces
Why is it important that homes are energy efficient
Because most of the energy in homes is thermal energy. This thermal energy is either created by burning coal, oil or gas or using an electric heater, for which the electricity is generated by burning coal, oil or gas.
Therefore, it is very important that the energy in a house is efficiently used to reduce environmental damage.
What are some of the properties of shiny objects in relation to thermal radiation
- They reflect thermal radiation
- They Absorb very little thermal radiation
- They do not radiate thermal radiation.
What are the main ways to increase efficiency in a house
- Loft Insulation inside walls or the roof.
- Windows with Double Glazing
- Thermostats and computer-controlled central heating systems.
- Making sure doors and windows fit correctly during installation.
- Reflective foil to prevent heat loss by radiation.
How does the wind significantly increase heat loss from the body
The wind makes air circulate around the body, very close to the skin. This causes very fast convection currents to occur, which causes hot air produced by the body to rise away from the body.
The wind may also cause sweat to evaporate from the body, causing a rapid cooling effect that is potentially fatal.
How do some animals reduce body heat loss
- Birds puff out their feather during the winter to trap a layer of air around their body to provide insulation and prevent heat loss.
- Penguins huddle together to provide warmth to each other.
- Some other animals curl into small balls to effectively reduce the surface area that is exposed to the environment
What are some uses of Convection
- Sea Breeze and Land Breeze
- Ground level Heaters
- Gliders
- Car Engines
What are insulators
These are poor conductors of heat
How do most insulators work
Most insulators contain pockets of trapped air. Air is a very bad conductor of thermal energy but a very good insulator of thermal energy. This means that conduction cannot occur.
The air is also trapped in the air pockets. This means that convection also cannot occur because the air cannot flow around.
