Chapter 2: Thermal Physics (Pt.3) Flashcards
How do you compare conductivity levels? Write the experimental method.
How do solids conduct thermal energy?
- Solids have a tight lattice-like structure meaning that they are not able to vibrate very far.
- Smaller vibrations means that they have lower temperature.
- In metals, their electrons detatch from the structure to carry this thermal energy throughout the structure, colliding with ions as they go.
What is required for thermal conduction to occur?
The particles need to be close together.
Why is air the worst conductor?
Because they are gases.
The particles in a gas are not close together so they do not easily collide with one another to pass on the energy.
They are the best insulators, therefore, we often use them in cavity walls of houses as well as in double-glazed windows.
What is a thermal conductor?
A material that readily transmits thermal energy
What is a thermal insulator?
A material that resists transmisson of thermal energy
List a feature of thermal conductors.
They have delocalised electrons which help them carry the thermal energy/charge to other particles in the solid.
What is convection?
The transfer of energy by the motion of a mass moving fluid, like a gas or liquid, causing energy to be carried and moved away from the source.
How are convection currents produced?
Convection above a hot surface happens when hot air expands, becomes less dense and rises.
Similarly in liquids, hot water is also less dense than cold water so it rises, forming convection currents.
How can we show convection currents in air?
Hoe can we show convection currents in water?
What is thermal radiation also known as?
Infrared radiation
Tell me the relationship between heat and the amount of radiation emitted.
The hotter the object, the greater the radiation emitted.
Can radiation pass through a vacuum? Why?
Yes, because it is a type of electromagnetic radiation which means that it involves waves to travel not particles.
Tell me the effect of the colour black on radiation.
The closer to the colour black a surface is, the more visible light it emits and absorbs.
