Physics P2 Flashcards
What process transfers heat through solids?
Conduction
What process transfers heat through liquids?
Convection
What process transfers heat through empty space?
Radiation
What does ‘Thermal conductivity’ mean?
Thermal conductivity is a measure of something’s ability to conduct heat
Give an example of a material which has a low thermal conductivity
Plastics
What is one similarity between conduction and convection?
They both involve particles gaining kinetic energy
What is one difference between conduction and convection?
Only energy is transferred in conduction. In convection the particles move.
What kind of heat transfer doesn’t require particles?
Radiation
What kind of waves does radiation use to transfer heat?
Infrared waves
Describe the process of conduction
Conduction is the process of heat being transmitted to neighbouring particles through collisions.
Why does conduction occur in solids but rarely in liquids and gases?
The particles in solids are held close together so there are lots of collisions which pass on the energy. Particles in liquids and gases are further apart so there are less collisions.
What type of wave is infrared radiation?
Electromagnetic wave
What does infrared radiation transfer and in what form?
It transfers thermal energy in the form of a wave
What materials are good at emitting infrared radiation?
Dark, matte materials
What materials are good at absorbing infrared radiation?
Light coloured, shiny materials
How would infrared radiation affect a black matte tube filled with water?
The infrared radiation would be absorbed by the surface and emitted into the surroundings, meaning the thermal energy is lost from the water and gets colder.
How would infrared radiation affect a shiny silver tube filled with water?
The infrared radiation is reflected by the shiny surface back into the liquid. Meaning more thermal energy stays in the water, so it is hotter for longer.
What are greenhouse gases and what do they do?
They are gases in the atmosphere that trap heat.
What 5 gases contribute the most to the greenhouse effect.
Water vapour (H2O)
Carbon dioxide (CO2)
Nitrous oxide (N2O)
Methane (CH4)
Ozone (O3)
Explain the process of the greenhouse effect
The sun’s radiation travels towards the Earth.
Some of the energy is reflected and the rest is absorbed by the Earth’s surface.
The Earth emits heat back into space but greenhouse gases trap it in the atmosphere, causing it to heat up.
When a substance is heated, it’s temperature rise depends on what?
The amount of energy supplied to it and the mass of the substance
What is the specific heat capacity of a substance?
The energy needed to raise the temperature of 1kg of the substance by 1C
What is the formula for calculating the specific heat capacity?
E = m c 0 (the 0 has a line going through the middle)
