Heat
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Presentation Transcript
Is energy HEAT You cannot see it But you can see its effect on matter © MDR PUBLISHING 2011
Heat makes matter change……. temperature state volume © MDR PUBLISHING 2011
ALL MATTER is made of PARTICLES Liquids Solids Gases These particles are continually moving © MDR PUBLISHING 2011
Temperature Is the amount of movement of particles High temperatures More movement Low temperatures Less movement © MDR PUBLISHING 2011
There is a temperature When the particles STOP MOVING This is called ABSOLUTE ZERO - 273 o C © MDR PUBLISHING 2011
Temperature is measured using a thermometer The bulb contains a liquid This heats up and expands into a capillary tube © MDR PUBLISHING 2011
Celsius calibrated the thermometer USING WATER He defined 0oC as 100 the freezing point of water And 100oC as 0 the boiling point of water © MDR PUBLISHING 2011
Temperatures can be changed in by…. Adding Heat, + Q Removing Heat, - Q © MDR PUBLISHING 2011
Or by…. Doing work, W © MDR PUBLISHING 2011
Thermal equilibrium Heat flows Until In a closed container Between objects They reach the same temperature 100oC 30oC 0oC 30oC
Changing state: solid to liquid As particles are heated They move faster And faster Until eventually They start to escape Into the Liquid State This is called melting It happens at the melting point © MDR PUBLISHING 2011
Changing state: solid to liquid Ice is heated and its At first its temperature increases Until it starts to melt The heat is used to help particles Change state This energy is called Latent HEAT of FUSION When ALL the ice has melted The temperature increasesagain temperature measured © MDR PUBLISHING 2011
Heat can move in three ways In solids In fluids In vacuum Conduction Convection Radiation © MDR PUBLISHING 2011
Conduction Heat is carried by FREE ELECTRONS Metals are good heat conductors They have many free electrons © MDR PUBLISHING 2011
Convection Air near the flame is heated and EXPANDS its density is less than the cold air around it And it rises © MDR PUBLISHING 2011
Radiation Matter is made of particles These particles vibrate And emit radiation © MDR PUBLISHING 2011
Everything that is warmer than absolute zero emits radiation EVERYTHING! © MDR PUBLISHING 2011
The particles in my hand vibrate And emit radiation At 35oC the radiation isn’t visible But a thermal camera can see it At about 1000 oC the radiation Becomes visible A light bulb filament reaches Over 3000 oC ? © MDR PUBLISHING 2011
