ENERGY Energy from the sun Carlo Waldfried Edited by Anne Starace Abstract Energy is an important concept in our everyday lives. This module demonstrates different forms of energy and also how energy can be transformed from one form to another. Keywords: energy, conservation of energy, solar energy Funded by the National Science Foundation and the University of Nebraska
Content Standards K 1 2 3 4 5 6 7 8 4.2.1 8.2.1 4.3.3 8.3.3 History & Process Standards K 1 2 3 4 5 6 7 8 4.6.2 4.7.2 Skills Used/Developed: 2
TABLE OF CONTENTS I.OBJECTIVES 4 II. SAFTEY..4 III. LEVEL, TIME REQUIRED AND NUMBER OF PARTICIPANTS...4 IV. LIST OF MATERIALS...4 V. INTRODUCTION...5 VI. PROCEDURE...Error! Bookmark not defined. VII. FREQUENTLY ASKED QUESTIONS. 7 VIII TROUBLE SHOOTING...7 IX. REFERENCES. 7 3
I. Objectives Students will: -learn about different forms of energy. -observe energy being converted from one form to another. -observe work done by solar energy. II. Safety Be gentle with the solar cells. The solar car is very fragile - use with caution. Make sure the car does not run into walls or table legs. Do not let younger students operate solar car. The 100 W lamp will become hot after long periods of operation be careful. III. LEVEL, TIME REQUIRED AND NUMBER OF PARTICIPANTS LEVEL This activity is appropriate for grades K-12. TIME REQURED No preparation is required. The activity takes from 10-20 minutes to complete. NUMBER OF PARTICIPANTS About 3-10 participants at a time solar cells, solar panel solar car fan (12 V DC, 60 ma) buzzer (24 V DC) IV. LIST OF MATERIALS lamp (100W) extension cord 4
V. INTRODUCTION Our world is under constant change, which is possible because there is energy available to be used in making the change. Without energy, the world would be completely static -- no changes could occur. This module explains the different forms of energy and how they can be used to make changes. The principle forms of energy can be categorized as: kinetic energy potential energy chemical energy heat (thermal) energy Although you cannot create or destroy energy (we say that energy is conserved ), energy can be transformed from one type of energy into another type. One of the important characteristics of energy is that it can be used to do work. Work is defined as force multiplied by distance. So basically, moving things is doing work; you must apply a force to make them move a certain distance. The harder you push and/or the farther you move something, the more work you are doing. Often, you cannot actually see energy, but you can measure energy by its ability to do work. The different types of energy have different features and to understand changes between these forms, we have to understand how each type of energy is different than the others. Type of energy description example kinetic energy energy of motion a moving car, a jogger potential energy energy of position: something that could potentially be pulled by gravity a piledriver, a bungee jumper just before the jump, a ball tossed into the air heat or thermal energy energy due to temperature boiling water, a hot piece of coal chemical energy energy stored in chemicals a battery, gasoline, food solar energy energy due to the sun solar cells Energy is constantly being transformed from one form of energy to another. For example, the human body uses food (which contains chemical energy) and converts it in our body into heat (body temperature), kinetic energy (motion), or into a different type of chemical energy - fat. The principle of conservation of energy is the most fundamental principle in the world. Its applications and usages are so common to our everyday life, that often it is not perceived. This module will help participants discover and explore various forms of energy and their interactions. 5
Energy from the Sun VI. PROCEDURE Setup: 1. Place the solar panel board with the attached fan and buzzer in bright sun light or under the 100 W lamp. 2. Connect the wires of the solar panel to either the fan or the buzzer. Make sure the wires are connected in the correct polarity (black to black and red to red). 3. Unpack the solar car. Execution: Expose the solar panel to intense light. Notice that the sound from the buzzer changes frequency as the incident light intensity (the position of the panel relative the light) varies. Remember: when the sunlight is blocked or the lamp is turned off the fan stops and/or the buzzer will be silent. The analog amp-meter and volt-meter can be used to find qualitative measurements of the electrical energy converted from the absorbed radiation energy by the solar panel. The solar car will start moving when its mounted solar panel is exposed to intense light. When in sunlight the solar car moves by itself until it reaches an area of shade where it will stop. If indoors, use the 100 W lamp (have a longer extension cord) and walk with the car. If you want the car to stop simply direct the light away from the solar panel. The angle of the solar panel can be adjusted for optimum light exposure. You can adjust the front axle so that the car moves in circles. This is an example of solar energy being converted to kinetic energy. Cleanup: 1. Turn off the lamp and let cool for several minutes (it will be hot!) 2. Carefully repack the solar panel board and the solar car. 6
VII. Frequently Asked Question Q. If you drove a solar powered car, what would you do when it was cloudy or night time? A. Solar panels can be made to store energy from the sun. When the sun is shining the panels store the energy from the sun, instead of immediately converting it, so that it can be used later when there is no sunlight. Many outdoor solar-powered lamps work this way in the daytime they gather energy from the sun and use that energy to light up when it gets dark. VIII. Trouble Shooting The fan does not turn when hooked up to the solar panel Make sure that red wires and connected with red and black with black. Try exposing the solar panel to more, brighter light. Give the fan a push to get it started while it is hooked up to the solar panel. IX. References For more solar energy activities and information: http://ofcn.org/cyber.serv/academy/ace/sci/cecsci/cecsci087.html http://www.ktca.org/newtons/14/olympicsolar09.html http://www.ktca.org/newtons/9/solarcar.html For information about energy and work: http://scienceworld.wolfram.com/physics/ (search for energy) To learn how solar cells work: http://www.howstuffworks.com/solar-cell.htm 7