1.2.2 Efficiency of Energy Transfers

    Cards (11)

    • What is efficiency a measure of?
      Energy conversion effectiveness
    • Efficiency is calculated as the useful output energy divided by the total input energy and then multiplied by 100%
    • In an energy transfer with 75% efficiency, 25% of the energy is dissipated as waste.
    • What is the principle of energy conservation?
      Energy cannot be created or destroyed
    • Energy dissipation often results in the production of heat or sound
    • What are the key points of energy conservation?
      Neither created nor destroyed
    • High friction leads to high energy efficiency.
      False
    • What is the formula for calculating energy transfer efficiency?
      Useful Output EnergyTotal Input Energy×100%\frac{\text{Useful Output Energy}}{\text{Total Input Energy}} \times 100\%
    • If a system has a total input energy of 300 J and a useful output energy of 210 J, its efficiency is 70%
    • Order the following examples from highest to lowest efficiency:
      1️⃣ LED Bulbs (90%)
      2️⃣ Energy Star Appliances (80%)
      3️⃣ High-Insulation Homes (75%)
      4️⃣ Hybrid Cars (50%)
    • LED bulbs are more energy-efficient than incandescent bulbs.