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Lesson 9 Energy Efficiency

Site: MoodleHUB.ca 🍁
Course: Science 10 [5 cr] - AB Ed copy 1
Book: Lesson 9 Energy Efficiency
Printed by: Guest user
Date: Sunday, 7 September 2025, 6:43 PM

Table of contents

  Introduction


What happens when an energy conversion occurs and it is not 100% efficient?

CS3.1 campfire
What form of energy is almost always released when an energy conversion occurs? A campfire keeps you warm on a cold night. The human body maintains a constant temperature through its body processes. Your hands get warmer as you rub them vigorously together. What do all of these situations have in common? Heat is being given off during all of these energy transformations.

In this section, we will look at the concepts of conserving energy and heat transfer to investigate, describe, and predict the efficiency of energy changes in technological systems.

  Targets


By the end of this section, you will be able to


CS3.2 old diesel engine

  1. describe current and past technologies used to transform energy from one form to another and identify that energy transfer technologies produce changes that can be measured in a system.

CS3.3 hydrogen fuel cell

  1. describe, in terms of the thermodynamic laws, the energy transformations occurring in devices and systems and identify that there is a limit to the amount of useful energy.

CS3.4 hydroelectric dam in Montreal, Canada

  1. explain, through calculations, efficiency as a measure of the useful work compared to the total energy put into an energy conversion process or device and analyze the efficiency of energy conversions and devices.
CS3.5 gas plant in Cochrane, Alberta

  1. compare the energy content of fuels used in thermal power plants in Alberta and explain the need for efficient energy conversions to protect our environment.

  Introduction

During any process, why is some energy converted into a form that is not useful?



C9.1 illuminated light bulb
All devices and machines are designed to convert one form of energy into another form in order to accomplish a specific task. No machine can convert all of one form of energy into the targeted form of energy, there will always be energy converted into forms that were not planned or not wanted. We as humans also waste a fair amount of energy in our day-to-day lives.

In this lesson you will look at the concepts of “useful” and “wasted” energy in energy transformations.

  Targets

By the end of this lesson, you will be able to

  • describe how the first and second laws of thermodynamics have changed our understanding of energy conversions
  • define “useful” energy from a technological perspective and analyze the stages of “useful” energy transformations in technological systems
  • recognize that there are limits to the amount of “useful” energy that can be derived from the conversion of potential energy to other forms in a technological device

  Watch This

The Surprising Places We Waste Energy © YouTube It’s Okay To Be Smart  


This video provides you with a great overview of the many ways that we waste energy. It also goes through possible solutions of how to decrease the amount of energy that we are wasting. This will help get you in the right mindset for this lesson.

  Energy Efficiency

No process can be 100% efficient—why?


C9.2 outdoor heat lamp
The meaning behind the second law of thermodynamics is that it is not possible to build a perfect machine—a machine that is 100% efficient. During any process, some energy is always converted into a form that is not useful to the end goal of the process. The first law of thermodynamics says that energy changes forms. But with every change, waste energy is produced.

The energy that performs the task that the process set out to accomplish is called useful energy.

The energy that is not useful to the end process is said to be waste energy.

If machines and engines are to have moving parts to produce mechanical energy, the moving parts rub against one another and produce friction. Friction produces heat. In most machines, heat from friction causes issues and is unwanted.

The initial energy source in a system is called energy input.

The desired energy needed to do the work is called useful energy output.

In any device that involves energy conversions, how many conversions are in a device is related to the efficiency of the device. The more conversions there are, the less efficient the device will be. Why?

With every energy conversion, the amount of useful energy output is less than the energy input. As discussed in Lesson 8, a food chain is a good illustration of this. With every level in the food chain, less useful energy is available for the next organism. In fact, with just 10% of the useful energy being transferred to the next level, a food chain is one of the least efficient natural systems.

  Virtual Activity

Household Energy Usage © Explore Learning


Work through this activity to compare the energy used by different types of light bulbs found in a typical household. You will determine which is most efficient by considering how much light it produces in relation to its wattage.

Traditional light bulbs are incandescent lamps. In this bulb, an electric current passes through a thin tungsten filament. The filament heats up and glows, giving off light.

In a halogen lamp, the filament is encased in a glass capsule containing pressurized gas. This allows the filament to be heated to higher temperatures and emit brighter light.

In a fluorescent lamp, an electrical current passes through a gas inside a phosphor-coated tube. The gas emits ultraviolet radiation, which causes the phosphor to glow.

Please note: if you scroll down while in the Gizmo you will see a list of questions. You DO NOT need to complete these questions. You are able to complete them for extra practice if you would like.


Procedure

Activity:
Comparing Light Bulbs
Get the Gizmo ready:
  • Click "Reset all appliances".
  • Check that the "BEDROOM" tab is chosen.
©Explore Learning
C9.3 image from lab of bedroom

Which kind of light bulb uses the least amount of energy?
  1. Click on the play icon to open the Gizmo. You can also access the Gizmo by visiting the Online Resources for Print Students section of your online course.
    1. Form a hypothesis: Which of the three types of lamps do you think is the most efficient?

      Hypotheses will vary. For example: I think that the halogen lamp will be the most efficient.
      Click on the gather data tab to continue.
    1. Gather data: On the "BEDROOM" tab, click on the incandescent light to the right of the laptop computer on the desk, and the halogen lamp at the head of the bed. Record the wattage of each. Then select the "KITCHEN" tab and record the wattage of the overhead fluorescent lamp.

      Note: A Watt is a measurement of the amount of energy used for every second the device is used. 1 Watt (W) = 1 Joule/second (J/s)

      Incandescent lamp:

      60 watts
      Halogen lamp:

      300 watts
      Fluorescent lamp:

      30 watts
      Click on the summarize tab to continue.
    1. Summarize: When the lamps are used for equal amounts of time, which one uses the most energy?

      Halogen lamp
    When the lamps are used for equal amounts of time, which one uses the least energy?

    Fluorescent lamp
    Click on the analyze tab to continue.
      1. Analyze: To gauge the efficiency of a light bulb, it is also important to consider how much light it produces. Light intensity is measured in lumens (lm). A lumen is equal to the light produced by a single candle. The lumens produced by each type of light are listed below.

        To compare the efficiency of each bulb, calculate how many lumens each bulb produces per watt. To do this, divide the number of lumens by the wattage for each lamp. Include all units.

        Sample Calculation:    «math» «mi»Lumens«/mi» «mo»§#160;«/mo» «mi»per«/mi» «mo»§#160;«/mo» «mi»watt«/mi» «mo»=«/mo» «mfrac» «mi»lumens«/mi» «mi»wattage«/mi» «/mfrac» «mspace linebreak=¨newline¨»«/mspace» «mi»Lumens«/mi» «mo»§#160;«/mo» «mi»per«/mi» «mo»§#160;«/mo» «msub» «mi»watt«/mi» «mrow» «mi»incandescent«/mi» «mo»§#160;«/mo» «mo»§#160;«/mo» «mi»bulb«/mi» «/mrow» «/msub» «mo»=«/mo» «mfrac» «mrow» «mn»800«/mn» «mo»§#160;«/mo» «mi»lm«/mi» «/mrow» «mrow» «mn»60«/mn» «mo»§#160;«/mo» «mi mathvariant=¨normal¨»W«/mi» «/mrow» «/mfrac» «mo»=«/mo» «mn»13«/mn» «mo».«/mo» «mn»33«/mn» «mo»§#160;«/mo» «mi»lm«/mi» «mo»/«/mo» «mi mathvariant=¨normal¨»W«/mi» «/math»

        Lamp Lumens (lm)
        		Wattage (W)
        		Lumens per Watt
        (lm/W)
        incandescent 800 lm


        halogen 6 000 lm


        fluorescent 2 000 lm




         
        Lamp Lumens (lm)
        		Wattage (W)
        		Lumens per Watt
        (lm/W)
        incandescent 800 lm
        		60 W
        		13.33 lm/W
        halogen 6 000 lm
        		300 W
        		20 lm/W
        fluorescent 2 000 lm
        		30 W
        		66.67 lm/W

      1. Which lamp produces light most efficiently?

        The fluorescent lamp is the most efficient.
      2. The fluorescent lamp is the most efficient.

        The incandescent lamp is least efficient.

  Digging Deeper

©Wikicommons CC0
C9.4 EnerGuide label

The EnerGuide label is the label you’ll find attached to most appliances. It tells you how much energy an appliance uses and makes it easier to compare the energy use of similar models of the same type of appliance.

The more energy efficient an appliance is, the less it costs to run and the lower your utility bills might be.

To learn more about EnerGuide labels, click on this link. https://www.nrcan.gc.ca/energy-efficiency/energuide-canada/energuide-label/13609

Learn More


  Read This

Please read page 215 in your Science 10 textbook. Make sure you take notes on your readings to study from later. You should focus on what useful energy and efficiency of a device or system are. Remember, if you have any questions, or do not understand something, ask your teacher!

  Practice Questions

Complete the following practice questions to check your understanding of the concept you just learned. Make sure you write complete answers to the practice questions in your notes. After you have checked your answers, make corrections to your responses (where necessary) to study from.

  1. Suppose you wanted to compare the efficiency of riding your bicycle compared to riding your skateboard. What would you measure as the energy input and what you measure as the useful energy output?

    Your answer should be a variation of the following.
    Energy input:the amount of chemical energy that you body used to provide the energy for you to ride the bicycle or skateboard
    Useful energy output: the amount of kinetic energy that the bicycle or skateboard has once in motion

  What Is Efficiency

There are no perfect machines—all machines produce waste energy.



C9.5 thermal image of high voltage power lines
There are limits to the amount of useful energy that can be formed from the conversion of potential energy to other forms in a technological device. With each energy conversion that occurs, more waste energy is produced, and therefore less useful energy is available.

Therefore, it is important to analyze the efficiency of energy transformations in a technological device, in order maximize the useful energy output. The next lesson in this section looks at how to calculate the efficiency of a device or system.

  Watch This

Bill Nye on Making His House Energy-Efficient © YouTube Wall Street Journal  


Watch this video for to see how Bill Nye has made his house energy-efficient to save money and to help the environment. He has implemented a number of devices and concepts discussed in this section of the physics unit so far.


3.6 Assignment

Unit 3 Assignment Lessons 9-11

It is now time to complete the Lesson 9 portion of 3.6 Assignment. This assignment has two parts.

  1. Part 1 Written Portion: Select the preferred document type from the options below. Download and save the assignment on your desktop (or documents folder).

    PDF Document       
  2. Open and print this saved document.
  3. Record your responses in the appropriate textboxes.
  4. When you have completed the assignment, scan it and save it on your desktop (or documents folder).
  5. Once you have completed the written portion of your assignment, click on the button below to go to the submission page.

    Written Portion Submission Page
  6. Part 2 Online Portion: It is now time to complete the online portion of this assignment. Click on the button below to go to the online questions of this assignment.

    Online Questions

This assignment is worth ___% of your final grade.