1.2.2

Energy Efficiency

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Efficiency of Energy Transfer

The efficiency of an energy transfer can never be more than 100. It is defined below:

Efficiency (energy in joules)

Efficiency (energy in joules)

  • Efficiency = (useful energy output/total energy input) x 100
    • The useful energy output and total energy input are measured in joules (J).
Efficiency (power in watts)

Efficiency (power in watts)

  • Efficiency = (useful power output/total power input) x 100
    • The useful power output and total power input are measured in watts (W).

Efficiency of Energy Transfer

The efficiency of an energy transfer can never be more than 100. It is defined below:

Efficiency (energy in joules)

Efficiency (energy in joules)

  • Efficiency = (useful energy output/total energy input) x 100.
  • The useful energy output and total energy input are measured in joules (J).
Efficiency (power in watts)

Efficiency (power in watts)

  • Efficiency = (useful power output/total power input) x 100.
  • The useful power output and total power input are measured in watts (W).
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1

Energy

1.1

Energy Changes

1.1.1Energy Stores1.1.2Energy Storing1.1.3Internal Energy1.1.4Kinetic Energy Storage1.1.5Gravitational Potential Energy Storage1.1.6Elastic Potential Energy Storage1.1.7Calculating Changes in Energy1.1.8Changes in Kinetic Energy - Calculations1.1.9Changes in GPE - Calculations1.1.10Changes in EPE - Calculations1.1.11Energy Transfers1.1.12Energy Transfer Examples1.1.13Conservation of Energy1.1.14Mechanical Work - Calculations1.1.15Mechanical Work Done1.1.16Mechanical Work Done Equation1.1.17Electrical Work Done1.1.18Power1.1.19Electrical Work Done- Calculations1.1.20Diagnostic Misconceptions - Stationary Objects
1.2

Energy Losses & Efficiency

1.2.1Energy Wastage1.2.2Energy Efficiency1.2.3Reducing Energy Loss1.2.4Power & Energy Transfer1.2.5Required Practical - Investigating Insulation1.2.6Efficiency - Calculations1.2.7Grade 9 - Energy & Efficiency
1.3

Energy Resources

1.3.1Energy Resources1.3.2Fossil Fuels1.3.3Geothermal Energy1.3.4Wind Energy1.3.5Water Energy1.3.6Tidal Energy1.3.7Nuclear Energy1.3.8Solar Energy1.3.9Original Source of Energy1.3.10Non-Renewable & Renewable Resources1.3.11Uses of Energy Sources1.3.12Changing Electricity Use1.3.13Renewable Energy1.3.14Limits to Renewable Energy Resources1.3.15End of Topic Test - Energy1.3.16Exam-Style Questions - Energy
2

Electricity

2.1

Electric Charge

2.1.1Circuit Diagrams2.1.2Circuit Symbols2.1.3Current2.1.4Current Equation2.1.5Current - Calculations2.1.6Conductors2.1.7Electrical Conductors - Electrons2.1.8Potential Difference2.1.9Voltage Equation2.1.10Measurements in Circuit2.1.11Voltage - Calculations2.1.12Diagnostic Misconceptions - Powering a Circuit
2.2

Resistance & Electrical Work

2.2.1Resistance2.2.2Measuring Resistance2.2.3Resistance Graph2.2.4Diodes2.2.5LDRs & Thermistors2.2.6Electrical Work2.2.7Power2.2.8Ohm's Law2.2.9Ohm's Law - Equation2.2.10Resistance & Ohms Law - Calculations2.2.11Electrical Work - Calculations2.2.12Required Practical - Investigating Resistance
2.3

Electric Circuits

2.3.1Series Circuits2.3.2Resistors2.3.3Required Practical - I–V Characteristics2.3.4Cells in Series2.3.5Series Circuits - Calculations2.3.6Parallel Circuits2.3.7Parallel Current2.3.8Parallel Resistance2.3.9Lights in Parallel2.3.10Parallel Circuits - Calculations2.3.11Grade 9 - Circuits2.3.12Exam-Style Questions - Electricity
2.4

Electricity in Homes

2.4.1AC/DC2.4.2Mains Electricity2.4.3Power Ratings2.4.4National Grid2.4.5Domestic Uses - Calculations2.4.6Fuses & Circuit Breakers2.4.7Fuse Ratings2.4.8Earthing2.4.9Dangers of the Live Wire2.4.10End of Topic Test - Electricity
2.5

Static Electricity

2.5.1Electrical Charge2.5.2Charging an Object2.5.3Charged Objects2.5.4Static Electricity2.5.5Electric Fields2.5.6Field Diagrams
3

Particle Model of Matter

3.1

States of Matter

3.1.1Atomic Model3.1.2Atomic Structure3.1.3Sub-Atomic Particles3.1.4Models of the Atom3.1.5Alpha Particles3.1.6Electron Arrangements3.1.7Density3.1.8Density Equation3.1.9Density & the Particle Model3.1.10Density - Calculations3.1.11Changes of State3.1.12Melting & Boiling3.1.13Exam-Style Questions - Density3.1.14Required Practical - Density3.1.15Diagnostic Misconceptions - Floating3.1.16Diagnostic Misconceptions - Volume
3.2

Heat

3.2.1Internal Energy3.2.2Change in Thermal Energy3.2.3Required Practical - Specific Heat Capacity3.2.4Equation for Heat Capacity3.2.5Leslie's Cube3.2.6Internal Energy - Calculations3.2.7Melting & Boiling3.2.8Latent Heat3.2.9Energy Change for Change of State3.2.10Latent Heat - Calculations3.2.11Specific Latent Heat of Fusion3.2.12Specific Latent Heat of Vaporisation
3.3

Particle Motion in Gases

3.3.1States of Matter3.3.2Properties of Gases3.3.3Temperature Increase in a Gas3.3.4Work Done on a Gas3.3.5End of Topic Test - Particle Model of Matter3.3.6Grade 9 - Particle Model of Matter3.3.7Exam-Style Questions - Specific Heat Capacity
4

Atoms & Radiation

4.1

Atoms

4.1.1Atomic Model4.1.2Structure of an Atom4.1.3Sub-Atomic Particles4.1.4Alpha Particles4.1.5The Model of the Atom4.1.6Electron Arrangements4.1.7Proton & Nucleon Numbers4.1.8Atoms & Ions4.1.9Isotopes 14.1.10Isotopes 24.1.11Carbon Nuclides4.1.12Exam-Style Questions - Atomic Structure4.1.13Diagnostic Misconceptions - Types of Radiation
4.2

Radiation

4.2.1Radioactivity4.2.2Types of Radiation4.2.3Detection of Radiation4.2.4Background Radiation4.2.5Types of Radioactive Emission4.2.6Ionising vs Penetration4.2.7Practical Applications of Radiation4.2.8Nuclear Fission4.2.9Nuclear Fission 24.2.10Nuclear Fusion4.2.11Radioactive Decay4.2.12Radioactive Decay Equations4.2.13Radioactive Decay Equations - Calculations4.2.14Radioactive Decay4.2.15Fission & Fusion Equations4.2.16Half Lives4.2.17Measuring Half Lives4.2.18Ionising Radiation4.2.19Half Life - Calculations4.2.20Safety Precautions4.2.21Uses for Isotopes With Different Half-lives4.2.22Radioactive Contamination & Irradiation4.2.23Types of Contamination4.2.24Required Practical - Radiation4.2.25Peer Review4.2.26End of Topic Test - Atoms & Radiation4.2.27Grade 9 - Radiation4.2.28Exam-Style Questions - Radioactive Decay
5

Forces

5.1

Basics of Motion

5.1.1Velocity5.1.2Average Speed5.1.3Adding Vectors5.1.4Acceleration5.1.5Distance vs Displacement5.1.6Contact & Non-Contact Forces5.1.7Contact Forces - Examples5.1.8Distance-Time Graphs5.1.9Speed-Time Graphs5.1.10Velocity - Time Graph5.1.11Average Speed - Calculations5.1.12Acceleration - Calculations5.1.13Uniform Acceleration - Calculations5.1.14Grade 9 - Motion5.1.15Exam-Style Questions - Motion5.1.16Diagnostic Misconception - Motion5.1.17Diagnostic Misconceptions - Acceleration
5.2

Forces

5.2.1Mass & Inertia5.2.2Weight5.2.3Centre of Mass5.2.4Gravity - Calculations5.2.5Resultant Forces5.2.6Newton's First Law5.2.7Newton Second Law - Calculations5.2.8Newton's Third Law5.2.9Free Body Force Diagrams5.2.10Free Body Diagram - Uses5.2.11Components of Forces5.2.12Free Body Diagrams - Calculations5.2.13Stretching a Spring5.2.14Elastic vs Inelastic Deformation5.2.15Hooke's Law & Equation5.2.16Hooke's Law - Equation5.2.17Hooke's Law - Calculations5.2.18Required Practical - Spring5.2.19Elastic Potential Energy5.2.20Elastic Potential Energy - Equation5.2.21Elastic Potential - Calculations5.2.22Exam-Style Questions - Elastic Potential Energy5.2.23Diagnostic Misconceptions - Weight & Mass
5.3

Effects of Forces

5.3.1Free Fall5.3.2Free Fall - Graphs5.3.3Air Resistance & Friction5.3.4Graphing Acceleration5.3.5Required Practical - Effects on Acceleration5.3.6Motion with Air Resistance5.3.7Momentum5.3.8Momentum: Law of Conservation5.3.9Force & Momentum Change5.3.10Momentum - Equation5.3.11Change in Momentum - Calculations5.3.12Momentum - Calculations5.3.13Turning Effect5.3.14Moments5.3.15Equilibrium5.3.16Moments - Calculations5.3.17Circular Motion5.3.18Levers & Gears5.3.19Gears5.3.20Stopping Distance5.3.21Factors Affecting Stopping Distance5.3.22Factors Affecting Braking Distance5.3.23Decelerations5.3.24Dangers of Large Decelerations5.3.25Stopping Distance - Calculations5.3.26Diagnostic Misconceptions - Upward Moving Objects
5.4

Pressure

5.4.1Pressure & Force on Container5.4.2Atmospheric Pressure5.4.3Liquid Pressure5.4.4Pressure - Calculations5.4.5Liquid Pressure - Calculations5.4.6Upthrust5.4.7Depth Control of Submarine5.4.8Pressure Difference5.4.9End of Topic Test - Forces5.4.10Exam-Style Questions - Pressure
6

Waves

6.1

Wave Basics

6.1.1Wave Basics6.1.2Wave Speed Formula6.1.3Wave Speed Equation6.1.4Wave Speed - Calculations6.1.5Wave Frequency Formula6.1.6Wavelength & Amplitude6.1.7Wave Frequency - Calculations6.1.8Transverse Waves6.1.9Longitudinal Wave6.1.10Required Practical - Ripple Tank6.1.11Diagnostic Misconceptions - Wavelength
6.2

Waves at a Boundary

6.2.1Waves at a Boundary6.2.2Waves at a Boundary 26.2.3Reflection of Light6.2.4Refraction of Light6.2.5Refraction of Light 26.2.6Internal Reflection6.2.7Required Practical - Reflection and Refraction
6.3

Sound Waves

6.3.1Sound Waves6.3.2Sound Waves & our Ears6.3.3Speed of Sound 16.3.4Speed of Sound 26.3.5Sound as a Wave6.3.6Uses of Sound Waves: Ultrasound Waves6.3.7Uses of Sound Waves: Earthquakes6.3.8Sound Waves - Calculations6.3.9End of Topic Test - Introduction to Waves6.3.10Exam-Style Questions - Wave Speed
6.4

Electromagnetic Waves

6.4.1Properties of Electromagnetic Waves6.4.2Gamma Rays6.4.3X-Rays6.4.4UV Light6.4.5Infrared Radiation6.4.6Microwaves6.4.7Radio Waves6.4.8Properties 26.4.9Visible Light6.4.10Visible Light 26.4.11Specular & Diffuse Reflection6.4.12Colours6.4.13Grade 9 - Waves
6.5

Lenses

6.5.1Lenses6.5.2Convex Lens6.5.3Concave Lens6.5.4Lenses - Calculations6.5.5Images6.5.6Ray Diagrams6.5.7Ray Diagrams 2
6.6

Heat & Radiation

6.6.1Infrared Radiation6.6.2Radiation & Surface Colour6.6.3Surface Area & Temperature6.6.4Temperature6.6.5Absorption & Emission6.6.6Greenhouse Effect6.6.7Energy Balance of the Earth6.6.8End of Topic Test - EM Waves, Lenses & Heat6.6.9Exam-Style Questions - EM Radiation
7

Magnetism

7.1

Magnetism Basics

7.1.1Magnetism7.1.2Magnetic Materials7.1.3Induced Magnetism7.1.4Magnetic Fields7.1.5Magnetic Field Patterns
7.2

Electromagnetism

7.2.1The Magnetic Effect of a Current7.2.2Solenoid Field7.2.3Magnetic Field Strength7.2.4Uses of Electromagnets7.2.5Motor Effect7.2.6Direction of Motor Effect7.2.7Magnetic Flux Equation7.2.8Magnetic Flux - Calculations7.2.9Electric Motors7.2.10Loudspeakers7.2.11Force Acting on a Coil in a Magnetic Field7.2.12Induced Potential Difference7.2.13Increasing the Induced Potential Difference7.2.14Magnetic Field Direction7.2.15Forces Between Electricity & Magnets7.2.16AC/DC7.2.17AC Generators7.2.18Generator Effect7.2.19Microphones
7.3

Transformers

7.3.1Transformers7.3.2Transformer Equation7.3.3Step-Up & Step-Down Transformers7.3.4Principles of Transformer Operation7.3.5High-Voltage Transmission & Transformers7.3.6Energy in Transformers7.3.7Power Losses in Cables7.3.8Transformers - Calculations7.3.9Transformers 2 - Calculations7.3.10End of Topic Test - Magnetism7.3.11Grade 9 - Transformers7.3.12Exam-Style Questions - Magnetic Fields
8

Astrophysics

8.1

Astrophysics

8.1.1The Solar System8.1.2The Sun8.1.3The Solar System - Calculations8.1.4Orbits8.1.5Stable Orbits8.1.6Orbits HyperLearning8.1.7Life Cycle of a Star like the Sun8.1.8Life Cycle of a Star Much Bigger than the Sun8.1.9Creation of Elements8.1.10Red-shift8.1.11The Big Bang Theory8.1.12Gaps in Knowledge8.1.13End of Topic Test - Astrophysics8.1.14Exam-Style Questions - Astrophysics

Practice questions on Energy Efficiency

Can you answer these? Test yourself with free interactive practice on Seneca — used by over 10 million students.

  1. 1
    How is efficiency most often expressed?Multiple choice
  2. 2
    Which of these quantities is considered in the equation for efficiency?Multiple choice
  3. 3
    Thomas Edison designed the first light bulb, which type of bulb did he invent?Multiple choice
  4. 4
    The new Samsung TVs primarily use quantum dots, which other energy-efficient feature do they use?Multiple choice
  5. 5
    Shanghai’s Maglev trains were first developed in 2004 reaching top speeds of 268mph, how did they reduce energy losses?Multiple choice
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Energy Wastage

Reducing Energy Loss