Scientific Method: Melting Chocolate & Energy Efficiency. Part 1. Name:

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1 Scientific Method: Melting Chocolate & Energy Efficiency Part 1 In this experiment we ll investigate the term energy efficiency and why incandescent light bulbs are less energy efficient compared to light emitting diodes (LEDs) by melting chocolate. However, before that we need you to answer the following questions. 1. In your own words, define these terms. a. Problem: _ b. Hypothesis: _ c. Experiment: _ d. Dependent Variable: e. Independent Variable: f. Data: _ g. Conclusion: _ 1

2 Part 2 Watch this Youtube video by Cree Inc. titled Chocolate Bunny Melts Under Incandescent Light, Survives LED Light. As you can see, the chocolate bunny melts under incandescent light, but survives under the LED light. In this experiment you have to determine why the chocolate bunny melts faster under incandescent light. 2. What is the problem you need to solve? Since Thomas Edison invented the carbon filament light bulb, incandescent light, or light generated by heating a metal wire to a temperature that causes it to glow, has dominated our lighting systems. But recently newer types of bulbs, such as CFL and LED bulbs, are starting to replace this 132 year old invention. The main reason is that these new bulbs are more energy efficient. But what does it mean to be energy efficient? 3. Create a hypothesis. What do you think causes the problem? 4. What do you think the term energy efficiency means? There is no wrong answer at this point. New light bulbs, such as LEDs directly convert electrical energy into light energy instead of the incandescent lights, which indirectly convert electrical energy into light, as they need to heat the metal up before it can light up. CFLs, the other most common energy efficient light, also directly convert electrical energy into light energy. However, CFLs use gases to help the light generation process while LEDs completely create light in a solid material. Light from heat or thermal energy, such as that of incandescent light, is very common. A great example of thermal energy to light energy is fire. We can see the light generated by fire as well as feel the heat it produces. For almost 300,000 years humanity used this 2

3 Compare your hypothesis with those suggested by others or with your whole class. Write down the two hypotheses that most people agree on could be the probable causes to your problem. Hypothesis 1: Hypothesis 2: When designing an experiment, scientists need to examine the educated guesses they made to determine all of the factors, or causes, that might prevent them from proving their guess was right. For example, when Thomas Edison was inventing the light bulb he needed to try many different approaches before he got it right. As the famous quote goes, Thomas Edison [did] not failed. [He] just found ways that won t work. After researching designs by previous light bulb inventors, Thomas Edison determined finding the right metal filament would create the most effective light bulb. In other words, he felt that the most effective light bulb would be dependent on the metal filament he chose. Thomas Edison also knew that to conduct his experiment, he needed all of the other pieces of the light bulb, such as the vacuum sealing, electrical contacts, and glass bulb, to remain the same while he only changed the metal filament he was experimenting with. 5. Design your experiment. a. What property will you test under each lamp to help you prove hypothesis 1 (in other words, what is hypothesis 1 s independent variable): b. What property will you test under each lamp to help you prove hypothesis 2 (in other words, what is hypothesis 2 s independent variable): c. Name the dependent variable (Hint: it s the same for both hypotheses): d. What will need to remain the same? Name 3 items. 3

4 Part 3 Have a teacher or responsible adult help you set up the experiment according to the setup guidelines sheet. 6. Make a rough sketch of your experiment 7. What equipment are you using to test: e. Hypothesis 1: f. Hypothesis 2: 8. Measure the height of the chocolate every 5 minutes. Time (minutes) Height LED (cm) Height Incandescent (cm)

5 9. Graph the heights of the three different groups as a function of time. Label each. 5

6 Part 4 Understanding the data you received is the most important part of any experiment. When Thomas Edison was designing the light bulb, he would not be satisfied with just seeing light produced by the metal filament. Thomas Edison also needed to know the life time of the filament, or how long the filament would continue to produce light. To do this, he needed to watch the various light bulbs for long hours and record the time it took for the light to go out. Thomas Edison would then compare the length of time to the metal filament he used until he decided that a carbon based filament would be the best solution to his problem. The graphs relating to the experiment and equipment you designed are provided to you by your teacher/helpful adult. Let s look at your data. 10. Under which light bulb did the chocolate shrink the fastest? 11. Compare this graph with the graphs provided to you. a. Which light bulb produced the most heat over time? b. Which light bulb produced the most light over time? 12. Which hypothesis is correct? Why? As you can see light bulbs are rated at different Watts. A Watt is a measure of electrical energy. However, electrical energy does not always equal the amount of light energy. That is why the incandescent light bulb, rated at 60 Watts, uses more energy than the LED light bulb, rated at 12 Watts, to produce the same amount of light. As energy must be conserved, where does the remaining energy go? The remaining energy is used up as heat. That s the reason why chocolate melts faster under an incandescent bulb than a LED bulb and why the energy cost for the incandescent bulb is much greater than the LED bulb. 13. What is energy efficiency? 14. How can we improve our homes to be more energy efficient? 6

7 Experimental Setup In this section the items and setup will be explained. You will need the following items: Incandescent Light Bulb LED Light Bulb (of similar equivalent wattage to incandescent) Two Similar Lamps Chocolate Bars (or Chocolate Bunny) Four blocks (if using a chocolate bars) Two paper or plastic plates (for the chocolate) Cardboard or equivalent light blocking divider Two Rulers Tape To compare the heat or light you will need one of the following Type 1: Thermometer Lightmeter Type 2: Arduino Uno (preferably any Adafruit Arduino Startup pack) Adafruit Data Logging Shield & SD card 2 TMP36 or equivalent Celsius temperature sensor 2 photocells or equivalent 2 10kΩ resistors 1 breadboard or equivalent Wires Arduino code from Triple Helix website It is recommended that you read LadyAda s logger shield tutorial at before using this setup. The Arduino sensor based portion is builds off of the Fridge Logger example. However, four sensors are used and wires are soldered to the four sensors to allow for their placement in the two locations. 7

8 Setup the experiment as follows: Type 1: Type 2*: * Datalogger not depicted. Follow online tutorials to setup Arduino. 8

9 Temperature (Celcius) Light Intensity (a.u.) Name: Arduino Demo Data: 1200 Amount of Light vs. Time Time (minutes) LED Incandescent Amount of Heat vs. Time Time (minutes) LED Incandescent 9