P3 - Thermal Physics Flashcards
Describe the particle arrangement of a solid [2]
Tightly packed in regular arrangement / particles cannot move but vibrate on the spot
Describe the particle arrangement of a liquid [2]
Close together but irregular / they can flow past each other
Describe the particle arrangement of a gas [2]
Separated with no regular arrangement / particles can move freely
How does density compare in solids, liquids and gases [1]
Solids are the most dense, then liquids, then gases
How does temperature affect the motion of particles [2]
As temperature increase, particles have more kinetic energy, so vibrate / move more
What is Brownian motion [2]
The constant and random movement of particles in a fluid resulting from collision between the particles
What is evaporation [1]
The escape of higher-energy particles from the surface of a liquid to form a gas
What happens when gases cool? [2]
They lose energy and condense back into a liquid
What happens if the volume of a fluid is decreased? [1]
The pressure increases (if temperature is constant)
What happens if the temperature of a gas is increased (at a constant volume) [1]
The pressure increases
Recall the equation that relates pressure and volume at a constant temperature [1]
pV = constant
What are the SI units for pressure? [1]
Pascals (Pa)
What are the SI units for volume? [1]
Metres cubed (m³)
What is thermal expansion? [3]
When a material is heated, the particles have more kinetic energy / so move more / resulting in more space between molecules
What state of matter experience the most thermal expansion and why? [2]
Gases because the particles have the most freedom to move
Describe how temperature is measured by liquid in glass apparatus [2]
As temperature rises the liquid expands / a scale is used to calibrate and convert expansion to a temperature value
Give examples of fixed points used to calibrate thermometers [2]
Melting point of water / Boiling point of water
Describe sensitivity [1]
The change in output per unit change in input
What is the sensitivity of a thermometer? [1]
The change in length per degree change in temperature
Describe how to increase the sensitivity of a thermometer [2]
Bigger bulb / narrower bulb
Define range [1]
The difference between the maximum and minimum values
How can the range of a thermometer be increased [2]
Wider bore / longer stem
Define linearity with an example [2]
When a change in input causes the same change in output (e.g. 1ᵒC produces a 1mm change)
What kind of materials can conduction occur in? [2]
Solids and liquids
Describe the process of conduction [3]
Solid or liquids is heated / particles vibrate more / energy is transferred to adjacent molecules via collisions transferring energy from hot to cold regions
In which materials can convection occur? [2]
In liquids and gases
Describe the process of convection [4]
When a section of fluid (liquid or gas) is heated it becomes less dense / this causes the fluid to rise / denser fluid falls to take its place and is then heated causing it to rise / this sets up a convection current
What kind of materials can transfer infrared radiation? [1]
Any kind of material, it does not require a medium
What is infrared radiation? [1]
An electromagnetic wave
What are the best absorbers of infrared radiation? [1]
Black, dull surfaces
What are the best emitters of infrared radiation? [1]
Black, dull surfaces
What are the best reflectors of infrared radiation? [1]
White, shiny surfaces
What factors affect the amount of infrared radiation emitted by a body? [2]
Temperature (higher = more IR) / Surface area (larger = more IR)
