Physics P1 Unit 1
- Created by: ola_k12
- Created on: 07-06-16 15:36
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- P1 Unit 1 Energy transfer by heating
- 1.2 Surfaces and radiation
- Light, shiny surfaces absorb less radiation than dark, matt surfaces
- Light, shiny surfaces reflect more infrared radiation than dark matt surfaces
- 1.3 States of matter
- Solid particles are held next to each other in fixed positions
- Have a fixed shape
- Liquid particles move at random but are in contact with eachother
- Takes shape of a container that it is in and can flow
- Gas particles move about randomly and are much further apart
- No fixed volume
- Solid particles are held next to each other in fixed positions
- 1.4 Conduction
- Metals conduct energy better than non-metals
- Metals contain free electrons
- Electrons move about at random inside a metal and hold the positive ions together
- Ions - an atom or molecule with an electric charge due to the loss or gain of one or more electrons
- When a metal is heated electrons spread out and collide with free electrons and ions in the cooler parts of the metal
- As a result, the electrons transfer kinetic energy to these electrons and ions
- Electrons move about at random inside a metal and hold the positive ions together
- In non-metals, the electrons are held in the atoms
- Energy only occurs when atoms vibrate and shake each other. That's why non-metals are good conductors
- 1.5 Convection
- Circulation of a gas or fluid caused by heating it
- Heat makes liquid or gas less dense which causes circulation
- Circulation of a gas or fluid caused by heating it
- 1.6 Evaporation and condensation
- Evaporation is when a liquid turns to gas
- Faster moving molecules are escaping from the liquid
- Evaporation can be increased by increasing the surface area of the liquid and increasing it's temperature
- Condensation is when gas turns into a liquid
- Condensation can be increased the area of the surface or reducing the temperature of the surface
- Evaporation is when a liquid turns to gas
- 1.7 Energy transfer by design
- The rate of energy transferred to or from an object depends on:
- The materials that the object is in contact with
- The temperature difference between the object and its surroundings
- The rate of energy transferred to or from an object depends on:
- 1.8 Specific heat capacity
- Change of temperature: E = m × c × theta
- c = E ÷ m × theta
- The greater the mass of an object, the more slowly its temperature increases when heated
- Rate of temperature change of a substance depends on:
- Energy supplied to it
- Its mass
- Its specific heat capacity
- 1.9 Heating and insulating buildings
- U-values tell us how much energy per second passes through different materials
- Energy transfer from our homes can be reduced by fitting:
- Loft insulation
- Cavity wall insulation
- Double glazing
- Draught proofing
- Aluminium foil behind radiators
- 1.2 Surfaces and radiation
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