GCSE Physics Unit 1 AQA

GCSE Physics Unit 1 AQA

1. Energy transfer by heating

   • Infrared radiation
     • Infrared radiation is energy transfer by electromagnetic waves
     • All objects emit infrared radiation
     • The hotter an object is the more infrared radiation it emits in a given time
   • Surfaces and radiation
     • Dark matt surfaces emit infrared radiation more quickly than light, shiny surfaces
     • Dark matt surfaces absorb infrared radiation more quickly than light, shiny surfaces
     • Light shiny surfaces reflect more infrared radiation than dark, matt surfaces
   • States of matter
     • Flow, shape, volume and density are the properties used to describe each state of matter
     • The particles in a solid are held next to each other, vibrating in their fixed positions
     • The particles in a liquid move about a random and are in contact with each other
     • The particles in a gas move about randomly are are much farther apart than particles in a solid or liquid
   • Conduction
     • Metals are the best conductors
     • Materials such as wool and fibreglass are good insulators
     • Conduction in a metal is mainly due to free electrons transferring energy inside the metal
     • Non-metals are poor conductors because they do not contain free electrons
   • Convection
     • Convection is the circulation of a fluid (liquid or gas) caused by heating it
     • Convection takes place only in liquids and gases (fluids)
     • Heating a liquid or a gas makes it less dense so it rises and causes circulation
   • Evaporation and condensation
     • Evaporation is when a liquid turns into a gas
     • Condensation is when a gas turns into a liquid
   • Energy transfer by design
     • The rate of energy transfer to or from an object depends on:
       • The shape, size and type of material of the object
       • The materials the object is in contact with
       • The temperature difference between the object and its surroundings
   • specific heat capacity
     • The greater the mass of an object, the more slowly its temperature increases when it is heated
     • The rate of temperature change in a substance when heated depends on the energy transferred to it, its mass and its specific heat capacity
   • Heating and Insulating buildings
     • The rate of energy transfer to or from our homes can be reduced
     • U-values tell us how much energy per second passes through different materials. The lower the U-value the better the materials as an insulator
     • Solar heating panels do not use fuel to heat water but they are expensive to buy an install