Topic 1 - Heat Flashcards
What is the structure of gas?
Well separated, no regular pattern
What is the structure of a liquid?
Close together, no regular pattern
What is the structure of a solid?
tightly packed, usually in a regular pattern
What is the movement of a gas?
Vibrates and moves freely at high speed
What is the movement of a liquid?
Vibrates, moves about and slides past each other
What is the movement of a solid?
Vibrates, generally doesn’t move from place to place
What is a thermal insulator? (give an example and an everyday example)
Something that prevents heat from moving from place to an another
E.g. Feathers and wood
Clothing and bedding
What is a thermal conductor? (give an example and an everyday example)
A material that transfers thermal energy well.
E.g. Aluminium, Copper
Saucepan, Radiator
What is expansion?
When a solid is heated the atoms begin to vibrate more. When this happens the atoms take up more space and the size of the material increases: it expands.
Explain how expansion takes place on railway tracks and why it is important?
Small gaps (called expansion gaps) are left between rails as the there is an expansion of the rails in hot weather
What is conduction and how does it work?
The thermal transfer of energy between neighbouring atoms. When atoms gain energy, they begin to vibrate more. When one atom collides with another, some of this energy is transferred.
Can conduction takes place in a vacuum? e.g. space
No, conduction can only take place where there is particles and the there are no particles in vacuum such as space.
What is radiation?
Heat transfer due to infra-red radiation
What surfaces are good absorbers and emitters of infra-red radiation?
Dark, matt surfaces
What surfaces are poor absorbers and emitters of infra-red radiation?
Light, shiny surfaces
Explain why convection cannot take place in solids
Convection cannot take place in solids because thr particles are not free to move
Describe the process of convection
- A fluid is heated. The temperature of the fluid increases and the particles begin to vibrate more.
- The particles move further apart. This reduces the density of the fluid.
- The warmer fluid begins to rise as it is less dense than the surrounding fluid.
- It is replaced by colder fluid moving underneath, which is then also heated.
- The warmer fluid at the top begins to cool, its density increases and it begins to sink.
This creates a cycle thar repeats.
Identify where conduction convection and thermal transfer by radiation are taking place
Conduction usually occurs in solids
Convection occurs fluids (liquids and gases)
Radiation occurs in a vacuum like space
