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Heat by Mind Map: Heat

1. Heat transfer

1.1. Radiation

1.1.1. Electromagnetic wave

1.1.1.1. Can travel through a vacuum

1.1.2. Matt black - best absorber and emitter

1.1.3. Shiny silver - worst absorber and emitter

1.2. Conduction

1.2.1. Energy transferred by particle collisions

1.2.1.1. Gases worst conductors becaues particles are far apart

1.2.1.2. Solids best conductors because particles joined togeter

1.2.1.2.1. Metals best conductors because of free electrons

1.3. Convection

1.3.1. Only happens in liquids and gases

1.3.1.1. Fluid expands, becomes less dense so floats upwards causing a convection current

2. House insulaton

2.1. Loft insulation

2.1.1. Fibres trap small pockets of air. Air is a gas so is a very poor conductor

2.1.2. Very cheap to install - pay back time about 1 year

2.2. Cavity wall insulation

2.2.1. Bubbles in the foam trap small pockets of air

2.2.2. Pay back time about 2 years

2.2.3. Most effective method of insulation

2.3. Double glazing

2.3.1. The air trapped between the two layers of glass is a very poor conductor

2.3.2. Very expensive - pay back time 10 to 20 years

2.3.3. Least effective method of insulation

3. Cooling

3.1. Temperature

3.1.1. The greater the difference in temp between the object and its surroundings the faster it transfers heat and cools down

3.2. Surface area

3.2.1. The greater the surface area of an object the faster it transfers heat so the faster it cools down