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1 1 KS3 SCIENCE - PHYSICS KS3 SCIENCE - PHYSICS Energy Transfer Energy Transfer

ENERGY TRANSFERS 2 2

3 3 Energy can never be created or destroyed - it is only ever converted to a different form Energy can never be created or destroyed - it is only ever converted to a different form

ENERGY TRANSFERS 4 4 Devices and machines convert energy from one form to another Devices and machines convert energy from one form to another DEVICE ENERGY INPUT ENERGY INPUT USEFUL ENERGY OUTPUT USEFUL ENERGY OUTPUT

ENERGY TRANSFERS 5 5 Devices and machines convert energy from one form to another Devices and machines convert energy from one form to another DEVICE ENERGY INPUT ENERGY INPUT USEFUL ENERGY OUTPUT USEFUL ENERGY OUTPUT Wasted energy - e.g. heat, sound Wasted energy - e.g. heat, sound However, they usually “lose” some However, they usually “lose” some

ENERGY TRANSFERS 6 6 E.g. fireworks convert chemical energy into kinetic and light energy E.g. fireworks convert chemical energy into kinetic and light energy DEVICE ENERGY INPUT ENERGY INPUT USEFUL ENERGY OUTPUT USEFUL ENERGY OUTPUT Wasted energy - e.g. heat, sound Wasted energy - e.g. heat, sound

ENERGY TRANSFERS 7 7 While domestic lamps are used to convert electrical energy into light energy While domestic lamps are used to convert electrical energy into light energy DEVICE ENERGY INPUT ENERGY INPUT USEFUL ENERGY OUTPUT USEFUL ENERGY OUTPUT Wasted energy - e.g. heat, sound Wasted energy - e.g. heat, sound

HEAT TRANSFER 8 8

9 9 “Conduction” is a process which occurs mainly in solids “Conduction” is a process which occurs mainly in solids Suppose heat is applied at one end of a solid rod Suppose heat is applied at one end of a solid rod

HEAT TRANSFER 10 The heat makes molecules vibrate faster at the hot end The heat makes molecules vibrate faster at the hot end “Conduction” is a process which occurs mainly in solids “Conduction” is a process which occurs mainly in solids

HEAT TRANSFER 11 This vibration is then passed along to neighbouring molecules This vibration is then passed along to neighbouring molecules “Conduction” is a process which occurs mainly in solids “Conduction” is a process which occurs mainly in solids

HEAT TRANSFER 12 So the heat gradually moves along the rod So the heat gradually moves along the rod “Conduction” is a process which occurs mainly in solids “Conduction” is a process which occurs mainly in solids

HEAT TRANSFER 13 Metals tend to be good conductors of heat Metals tend to be good conductors of heat

HEAT TRANSFER 14 “Convection” of heat only happens in liquids and gases “Convection” of heat only happens in liquids and gases Suppose we heat some water in a pot Suppose we heat some water in a pot

HEAT TRANSFER 15 “Convection” of heat only happens in liquids and gases “Convection” of heat only happens in liquids and gases This area of water heats up so it expands This area of water heats up so it expands

HEAT TRANSFER 16 “Convection” of heat only happens in liquids and gases “Convection” of heat only happens in liquids and gases Once expanded it is less dense, so each ml of it weighs less and it tends to rise Once expanded it is less dense, so each ml of it weighs less and it tends to rise

HEAT TRANSFER 17 “Convection” of heat only happens in liquids and gases “Convection” of heat only happens in liquids and gases Colder water sinks and is itself heated, also as the hot water rises, it transfers its heat to surrounding molecules through the process of conduction Colder water sinks and is itself heated, also as the hot water rises, it transfers its heat to surrounding molecules through the process of conduction

HEAT TRANSFER 18 “Radiation” of heat is caused by electromagnetic waves in the infra-red part of the spectrum “Radiation” of heat is caused by electromagnetic waves in the infra-red part of the spectrum

HEAT TRANSFER 19 “Radiation” of heat is caused by electromagnetic waves in the infra-red part of the spectrum “Radiation” of heat is caused by electromagnetic waves in the infra-red part of the spectrum White materials reflect a lot of radiation and stay cooler White materials reflect a lot of radiation and stay cooler

HEAT TRANSFER 20 “Radiation” of heat is caused by electromagnetic waves in the infra-red part of the spectrum “Radiation” of heat is caused by electromagnetic waves in the infra-red part of the spectrum Darker materials absorb radiation and heat up Darker materials absorb radiation and heat up

HEAT TRANSFER 21 “Radiation” of heat is caused by electromagnetic waves in the infra-red part of the spectrum “Radiation” of heat is caused by electromagnetic waves in the infra-red part of the spectrum Radiation passes through transparent materials and also through a vacuum Radiation passes through transparent materials and also through a vacuum