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Lesson: Chapter 10 — Power and energy in electrical appliances

10.3. Efficiency and saving energy 3 of 3

Saving energy

Efficiency

If 40% of the electrical energy supplied to an appliance is wasted as heat, only 60% goes into the job: its efficiency is 60%.

Unless heat is what we want, we should cut the energy wasted as heat and get as much work as possible out of the energy supplied.

Everyday ways to save

  • Iron a whole week's clothes at once, to save the energy of heating the iron up again and again.
  • Switch lamps off when they are not needed.
  • Use efficient lamps (LED, CFL) that give only the light needed.
  • Choose the appliance that does the job with the least energy — it helps with the coming energy crisis.

Assignment 10.1

List the electrical appliances in your home and write each one's power beside it, from its rating label or instruction leaflet — or ask an adult.