Download IGCSE PHYSICS ENERGY DEFINITIONS AND

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IGCSE PHYSICS ENERGY RESOURCES AND ENERGY
TRANSFER DEFINITIONS AND CONCEPTS
FORMS OF ENERGY: Energy is transferred from one form to another whenever
any change happens. forms of energy include chemical, nuclear, light, sound,
magnetic, thermal, electrical, kinetic and potential. Measured in joules.
CONSERVATION OF ENERGY: Energy is never created nor destroyed, it just
transfers from one form to another.
EFFICIENCY: A measure of the fraction of useful work a machine does.
ENERGY FLOW (SANKEY) DIAGRAMS: A diagram which shows the energy
transfers in a system and its environment.
THERMAL ENERGY TRANSFER: Thermal energy can be transferred by
conduction, convection and radiation.
CONDUCTION: Occurs chiefly in solids, by interaction between the particles
which transfers thermal energy.
CONVECTION: Occurs in fluids (liquids and gases), warm fluid expands and rises
and is replaced by denser cooler fluid which sinks.
RADIATION: Does not require a medium. Energy is transferred by
electromagnetic radiation traveling at the speed of light.
THERMAL INSULATION: Materials which slow down the transfer of thermal
energy.
WORK: Work is done when a force moves.
WORK AND ENERGY: The work done is a measure of the amount of energy
transferred.
JOULE (J): The unit of work and energy. 1 joule is the work done when a force of
1 newton moves through 1 metre. 1J = 1Nm
GRAVITATIONAL POTENTIAL ENERGY: Energy which an object has due to its
position in a gravitational field.
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ELASTIC POTENTIAL ENERGY: Energy which an elastic object has when it is
stretched or squashed.
KINETIC ENERGY: Energy which an object has due to its motion.
POWER: The rate of doing work or the rate of transferring work from one form
to another.
WATT: The unit of power. 1 watt = 1 joule per second.
RENEWABLE ENERGY RESOURCES: These cannot be exhausted and are
generally non-polluting. eg solar, wind, wave, tidal, hydroelectric, geothermal,
biomass.
NON-RENEWABLE ENERGY RESOURCES: Once used up, these cannot be
replaced. eg oil, natural gas, coal.