3.2 Efficiency

• What does efficiency measure?

  Energy conversion effectiveness
• Match the energy type with its explanation:

  Total Energy Input ↔️ Total energy entering a system

  Useful Energy Output ↔️ Energy converted to desired form
• What is the purpose of useful energy in a system?

  Perform a specific task
• What does the formula for efficiency measure?

  Energy conversion effectiveness
• A device with 100J input and 70J output has 70% efficiency.


  True
• Wasted energy contributes to the intended task of a system.

  False
• Wasted energy does not contribute to the intended task
• The efficiency formula is expressed as a percentage


  True
• What is the efficiency if a device consumes 100J and provides 70J of useful work?

  70%
• One factor affecting efficiency is friction
• What are strategies to reduce friction in a system?

  Lubricants, design, maintenance
• What does efficiency measure in the context of energy conversion?

  Effectiveness of conversion
• What does efficiency measure in energy conversion?

  How effectively energy is converted
• Match the energy concept with its explanation:

  Efficiency ↔️ Measures how effectively energy is converted

  Total Energy Input ↔️ The total energy that enters a system

  Useful Energy Output ↔️ The energy that successfully performs the task
• Heat loss reduces efficiency by dissipating energy into the environment.


  True
• Steps to reduce friction and improve efficiency

  1️⃣ Use lubricants between moving parts

  2️⃣ Improve component design

  3️⃣ Maintain equipment regularly
• The efficiency formula allows us to quantify how effectively a device converts energy from the total input to the useful output
• Efficiency is expressed as a percentage or decimal fraction.


  True
• Efficiency measures the effectiveness of energy conversion from total energy input to useful energy output
• Match the wasted energy form with its description:

  Heat ↔️ Energy lost due to temperature

  Sound ↔️ Energy lost as noise

  Friction ↔️ Energy lost due to resistance
• Arrange the following steps in calculating efficiency:

  1️⃣ Identify Total Energy Input

  2️⃣ Identify Useful Energy Output

  3️⃣ Apply the efficiency formula

  4️⃣ Calculate efficiency as a percentage
• In an incandescent bulb, only 5% of the energy is used for light, while 95% is wasted as heat
• What is useful energy opposed to?

  Wasted energy
• What does the efficiency formula measure?

  Energy conversion effectiveness
• Order the concepts from the efficiency formula from input to output:

  1️⃣ Total Energy Input

  2️⃣ Useful Energy Output

  3️⃣ Efficiency
• What is the efficiency of a laptop that requires 150J and provides 120J of useful work?

  80%
• Match the factor affecting efficiency with its impact:

  Friction ↔️ Reduces kinetic energy

  Heat Loss ↔️ Dissipates energy

  Material Properties ↔️ Affects conductivity

  Design and Maintenance ↔️ Increases energy waste
• How is efficiency expressed in quantitative terms?

  Percentage or fraction
• Wasted energy is lost as heat, sound, or friction
• What is useful energy output?

  Energy that performs the task
• Efficiency equals the ratio of useful energy output to total energy input, multiplied by 100
• Friction reduces efficiency by converting kinetic energy into heat
• What is the efficiency of an LED bulb compared to an incandescent bulb?

  80% vs 5%
• The efficiency formula is: Efficiency = (Useful Energy Output / Total Energy Input) x 100%
• What is useful energy?

  Energy performing intended task
• Useful energy is wasted as heat or friction during energy conversion.

  False
• The efficiency formula is: Efficiency = (Useful Energy Output / Total Energy Input) x 100%
• What is the role of useful energy in energy conversion?

  Perform a specific task
• What are common forms of wasted energy?

  Heat, sound, friction
• Match the common forms of wasted energy with their examples:

  Heat ↔️ Engine overheating

  Sound ↔️ Noise from a motor

  Friction ↔️ Parts rubbing together