Energy and Efficiency

energy being transformed or transfered and the efficieny

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  • Created by: Harri
  • Created on: 07-06-11 20:27

Energy Transfer

  • electric fire = electric energy to heat energy
  • falling object = gravitational potential energy to kinetic energy
  • battery = chemical energy to electric energy
  • dynamo = kinetic energy to electric energy
  • tree = light energy to chemical energy
  • hitting drum = kinetic energy to sound energy
  • hot object = heat energy to light energy
  • light bulb = electric energy to light energy
  • electric motor = electric energy to kinetic energy
  • leg muscles = chemical energy to kinetic energy
  • catapult = strain energy to kinetic energy
  • glow worm = chemical energy to light energy
  • loudspeaker = electric energy to sound energy
  • sound absorbing cloth = sound energy to heat energy
  • atom bomb = nuclear energy to kinetic/light/heat/sound energy
  • gas fire = chemical energy to heat energy
  • steam engine = heat energy to kinetic energy
  • friction = kinetic energy to heat energy
  • microphone = sound energy to electric energy
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Energy and Efficiency

Energy cannot be created or destroyed, only transfered between different forms. energy tends to dissapate (spread) as less useful forms i.e. heat.

forms of energy


chemical, atomic/nuclear, movement/kinetic, electric, light, sound, gravitational potential (GPE), - , thermal/heat, streatch/elastic potential energy (EPE)

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no device transfers energy with 100% efficiency. some energy is always wasted, maily a heat that dissapates into the environment

we calculate the efficiency by:

efficiency = (useful energy out/total energy in) x100


100J electric energy → lightbulb → 70J heat

                                                    → 30J light

30/100 x100            this lightbulb is 30% efficient



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