Heat is a form of energy that is transferred between objects due to a temperature difference. Heat causes materials to expand and contract as it is absorbed or lost. There are three main methods of heat transfer: conduction, convection, and radiation. Conduction involves direct contact between objects, convection involves the transfer of heat by fluid movement, and radiation involves the transfer of heat through electromagnetic waves without direct contact. Temperature is a measurement of the average kinetic energy of particles in a substance and can be measured with thermometers on different temperature scales.

1. Heat and temperature CONTENTS RESOURCES

2. CONTENTS Heat and temperature Heat Definition Measurement Effects of heat Effects on matter Expansion and contraction Changes of state Heat transfer Conduction Conductors and insulators Convection Radiation Temperature Temperature and mearurement Thermometers Temperature scales

3. RESOURCES Expansion and contraction Changes of state Temperature scales Conduction Convection Radiation Heat Heat measurement Conductors and insulators Temperature and measurement Thermometers Effects of heat Links Heat and temperature

4. Heat Heat is the amount of thermal energy that is transferred from one body or system to another, due to a difference in temperature. Heat is energy in transit. SEE ANIMATION

5. Heat Heat is energy in transit. Heat flow stops when their temperatures are the same, that is, thermal equilibirum. Heat flows from the hot iron rod to the cold water. Heat is the amount of thermal energy that is transferred from one body or system to another, due to a difference in temperature. GO BACK

6. Heat measurement 1 J = 0.24 cal Units of heat: joules (J) calories (cal) Heat is measured in units of joules or calories . 1 cal = 4.186 J heat

7. Temperature and measurement Temperature is the amount of heat in a system. Temperature can be measured with a thermometer.

8. Thermometers coloured alcohol mercury Alcohol thermometer Clinical thermometer They are used to measure atmospheric temperature. X [close] They are used to measure body temperature. X [close]

9. Temperature scales ºF ºC K Fahrenheit scale (ºF) 212 176 140 104 68 32 Boiling point Freezing point water Celsius scale (ºC) Kelvin or absolute scale (K) 373 353 333 313 293 273 100 80 60 40 20 0

10. Effects of heat Heat produces the following effects on matter: Expansion Contraction

11. Effects of heat Heat produces the following effects on matter: Expansion: The increase in volume which occurs when a system gains heat. Expansion Contraction

12. Effects of heat Heat produces the following effects on matter: Contraction Contraction: the decrease in volume which occurs when a system loses heat. Expansion

13. The gas inside a balloon expands when heated. Expansion and contraction The particles move more freely than in solids. Liquids usually expand more than soilds. The particles are far apart and move more freely than in liquids. Gases usually expand more than liquids. The particles are not free to move. Solids do not expand much. Solids Liquids Gases Mercury expands when heated. Expansion joints expand when it is hot. WHAT HAPPENS WHEN RAILS CONTRACT? WHAT HAPPENS WHEN A GAS EXPANDS?

14. The gas inside a balloon expands when heated. Expansion and contraction The particles move more freely than in solids. Liquids usually expand more than soilds. The particles are far apart and move more freely than in liquids. Gases usually expand more than liquids. The particles are not free to move. Solids do not expand much. Solids Liquids Gases Mercury expands when heated. Expansion joints expand when it is hot. The particles move more slowly and occupy less space. The volume decreases, and the rails contract. WHAT HAPPENS WHEN A GAS EXPANDS? The rails cool. X [close] 0 10 0 10

15. The gas inside a balloon expands when heated. Expansion and contraction The particles move more freely than in solids. Liquids usually expand more than soilds. The particles are far apart and move more freely than in liquids. Gases usually expand more than liquids. The particles are not free to move. Solids do not expand much. Solids Liquids Gases Mercury expands when heated. Expansion joints expand when it is hot. When gas expands, the volume increases. This can push a cork out. WHAT HAPPENS WHEN RAILS CONTRACT? Gases X [close]

16. Changes of state When a state of matter gains or loses heat, it undergoes a change. SOLID LIQUID GAS melting solidifcation sublimation desublimation evaporation condensation endothermic exothermic Heat changes can be:

17. Conduction Direction of heat The kinetic energy of the particles increases. particles of a solid This is the transfer of heat in most solids. Heat is transferred by direct contact .

18. Conductors and insulators Insulators do not allow heat to move through them easily. Conductors allow heat to move through them easily. metal plastic Double-glazed window air air space cork

19. Convection gas particles liquid particles convection currents This is the transfer of heat in liquids and gases. Heat is transferred by the movement of currents.

20. Greenhouse Radiation solar radiation radiation emitted by plants This is the transfer of heat by electromagnetic waves. No contact is necessary between the source and the heated substance.

21. Links How is heat transferred http://antonine-education.co.uk/Physics_GCSE/Unit_1/Topic_1/topic_1_how_is_heat_transferred.htm Heat transfer activities http://www.reachoutmichigan.org/funexperiments/agesubject/lessons/caps/htransfer.html Transfer of thermal energy http://www.bbc.co.uk/schools/ks3bitesize/science/physics/energy_transfer_4.shtml Heat http:// www.leavingcert.net/skoool/examcentre_jc.asp?id =4091 Hands-on physics: Heat & temperature http://hop.concord.org/h1/phys/h1p.html Thermodynamics http://www.arborsci.com/CoolStuff/cool26.htm Solids, liquids and gases and the particle theory http:// www.worsleyschool.net/science/files/state/changes.html Heat and temperature http://coolcosmos.ipac.caltech.edu//cosmic_classroom/light_lessons/thermal/index.html