AQA Physics Unit 1 - Heat Transfer's

AQA Physics Unit 1 - Heat Transfer's 

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  • Created by: PhilMoze
  • Created on: 15-01-11 23:42

Conduction

 (http://cfbt-us.com/wordpress/wp-content/uploads/2010/03/metal_conductivity_lr.jpg)

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Conduction Two

 

 

 

This is where heat is transfered without the object moving. 

Metals are good because: 

CLOSE ATOMIC STRUCTURE

FREE ELECTRONS

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Convection

        Particles Move in this transfer. Density changes. Heat = less dense because of more movement. At the top it cools, less energy, more dense and sinks. To Create a current.    HAPPENS IN FLUIDS                                                         (http://www.teachersparadise.com/ency/en/media/1/12/convection_cells.png)

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Radiation

 

HEAT IS TRANSFERRED AS INFA-RED RADIATION

Electromagnetic Wave

 

All object's absorb and give off heat radiation.

 

Dark Surfaces = Absorb more, and emit more

Light Surfaces = Reflect more, and emit less. 

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Heat Loss In House

WE CAN SAVE HEAT (AND ENERGY) BY:

 

ROOF - roof insulation (20% reduction, expensive)

DOOR AND WINDOW - Draught Excluders (15% and Cheap, need fresh air still!)

WALLS - Wall insulation (35%, expensive)

WINDOWS - Double Glazing (10%, expensive)

FLOOR - Carpet (easy to install, expensive)

 

EACH OF THESE INSULATES THE HOUSE

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Heat Insulation Design

THERMOS FLASK

These are designed to keep in heat, (OR KEEP OUT). 

It uses VACUUMS. (STOP'S CONDUCTION, can't travel through Vacuum, STOP CONVECTION, No particles)

It uses Shiny Surfaces. (DOESN'T ABSORB HEAT IN FLASK, REFLECT'S BACK INWARDS).

(http://www.probertencyclopaedia.com/j/Vacuum-flask.jpg)

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